Roomba s9+ robot vacuum review: The most expensive Roomba vacuum is worth every penny, according to our vacuum expert

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In 2002, iRobot introduced the first Roomba. Since then, the brand name Roomba has become synonymous with "robot vacuum." Though dozens of other brands have entered the space, iRobot continues to stay ahead of the innovation curve and regular earns spots in our guide to the best robot vacuums.

In September 2018, iRobot introduced the Roomba i7+, which was the first robot vac that featured a charging dock that emptied the dustbin. Based on feedback, iRobot made tweaks to the design and features of the i7+ and launched a new top-of-the-line model, the s9+, in October 2019.

The Roomba s9+ is innovative because it has increased suction power, a D-shaped design, two long main brushes with unique positioning, and a longer-lasting battery. I've tested the s9+ for several months now — it's the main vacuum I use when not testing other models — and here's what I like about it.

Design and specs

There are a few design choices that make the s9+ different from other Roombas. The most obvious one is the D shape, which is supposed to help it get deeper into corners. The unit is remarkably small at 12.5 inches in diameter, but the height is comparable to other units at 3.5 inches.

The small body size is impressive considering that it has two of the longest main brushes I've seen at 9.5 inches each. The brushes are located closer to the front of the unit than most other robot vacuum models. The forward design and length of the brushes are supposed to facilitate better corner cleaning and make it easier for the robot to pick up debris on a single pass.

Though iRobot doesn't give precise suction power measurements for its robots, it claims that the s9+ has suction 40 times more powerful than the Roomba 600 Series and four times more powerful than the next strongest Roomba and s9+ predecessor, the i7+.

The Roomba s9+ comes with a Clean Base that charges the robot and empties its dustbin. The box also contains an extra high-efficiency filter, an extra side brush, and an extra dirt disposal bag.

Setup process

Setting up the Roomba s9+ took longer than most robot vacuums I've tested, but I still had it up and going in under half an hour. After unboxing the elements and finding a spot for the Clean Base, I plugged it in and set the vac on the charging dock.

Next, I downloaded the iRobot app and installed firmware updates. The updates took the bulk of the setup time. Once they were installed, I scheduled the s9+ to clean daily, which was an effortless task taking only a few seconds.

I liked that when I scheduled the vac, it let me choose how powerful the suction is. On its lowest setting, the battery lasts for two hours. On the highest setting, it only runs for about 45 minutes. I chose the highest setting, and since I have more space than the Roomba can clean in 45 minutes, it just returns to the dock to charge and automatically finishes the cleaning cycle once it has enough juice.

Connecting to Amazon Alexa was a seamless process. I just added the iRobot skill in the Alexa app, and it was ready to go.

Cleaning with the iRobot Roomba s9+

The most important feature of any robotic vacuum is its performance. How well can it pick up debris on a variety of surfaces? To test this, I pour a tablespoon each of flour, kitty litter, and coffee grounds along with pet hair on low-pile carpeting and hardwood flooring. Then, I run the vacuum on high for two cleaning cycles, measure the contents accumulated in the robot's dustbin, and compare before and after photos to estimate how much of the debris the vacuum picked up.

On hardwood, the Roomba s9+ did better than any vacuum I've ever tested. All of the kitty litter, pet hair, and coffee grounds were gone, and I only found a trace of flour left over. The performance on carpeting was only slightly less impressive. Gone were the coffee grounds and pet hair. Only around 5% of the kitty litter and 10% of the flour were left behind.

I also tested how well the s9+ does at cleaning corners by sprinkling a teaspoon of flour into hardwood and carpeted corners. Though the D-shaped vac came within an inch of the carpeted corner, it only picked up about 30% of the flour. This is likely due to the powerful main brush not coming into direct contact with debris. On the other hand, on hardwood, the unit did much better, picking up around 85% of the flour and coming within 1.5 inches of the corner.

The s9+ rarely gets stuck. On our testing course, which contains cords and other obstacles, it did not get stuck at all. And, in my daily use, it tends to only run into issues when one of my messy family members leaves clothes on the floor. The s9+ will try to suck them up, and I'll get a notification that the main brushes need to be untangled. This is easy enough to fix.

In addition to performing well, the Roomba s9+ is packed full of features that work as advertised. My favorite feature is the Clean Base, which serves as the charging dock and empties the vac's dustbin. The dust is collected in a disposable dirt bag, which you only need to replace every month or two when the app notifies you.

The iRobot app is among the best robot vacuum apps I've used. You can use it to do basic tasks, like schedule cleanings, as well as more complex functions. For instance, once the s9+ maps your home, which can take several cleaning cycles, you can schedule it to clean specific rooms at certain times. I also liked that I could set no-go zones that the unit would automatically avoid.

Cons to consider

The biggest negative with the Roomba s9+ is how loud it gets. On its highest suction setting, my sound meter measured 77 decibels, which is comparable to heavy city traffic. The vac was better on its lowest setting at 64 decibels — about the same as a normal conversation. In my testing, I've found stronger suction is usually correlated with louder operation, and that appears to hold true with the s9+.

It took at least four cleaning cycles for the s9+ to be able to map the layout of my home. This was annoying because, in the meantime, I couldn't set no-go zones, and I had some areas with several wires that the vac would get caught up on. Fortunately, I was able to set no-go zones eventually, and the robot did a good job of obeying them.

What are your alternatives?

Robot vac technology is changing all the time, so check out our guide to the best robot vacuums for our most up-to-date recommendations. I'd like to add that Roomba also has a more affordable self-emptying Roomba, the i3+ (currently $499.99 on Amazon). At nearly half the price of the s9+, you sacrifice some mapping capabilities and suction power, but it's still an impressive device that performs better on carpeting than any of the other vacs I've tested.

The bottom line

Despite these minor negatives, I think the Roomba s9+ is one of the best robot vacuums available. I especially like that it empties the dustbin itself so I don't have to remember to stay on top of that between cleanings.

The s9+ is one of the most expensive robot vacuums on the market. Even the most affordable robovacs are luxury items and do not replace traditional upright models. So, we mostly just recommend the s9+ to consumers who have significant expendable income and want a low-fuss device that automates the chore of vacuuming. The s9+ is also a great option if you simply must have the most innovative gadgets. It's the top-of-the-line model from the top name in robot vacuums.

Robot vacuums are usually deeply discounted during the major sale days, such as Black Friday, Cyber Monday, and Amazon Prime Day. So, if the s9+ is just outside of your price range and you don't mind waiting, keep your eyes peeled for deals.

Pros: Features a useful app with virtual no-go zones, large main brushes, charging dock that empties the unit's dustbin, does better on hardwood floors than any other vac we've tested, good performance on carpeting

Cons: Didn't clean carpeted corners well in our tests, loud, takes several cleaning cycles to create a floor map