The S9 was (and is) marketed as the first major, revolutionary design update in iRobot's long history of robot vacuum making. It could not be a more unusable product in practice.
I've owned 4 generations of Roomba's now, the 650, the 891, the i7 (that I purposely 'downgraded' from the S9), and the S9. To me, iRobot is unmatched in the robot vacuum game. Their cleaning algorithm is the secret sauce, I don't care how much more power or dirt capacity or battery life a competitor has, iRobot's vacuums outmaneuver them every time. Every one of their models are unbelievably solid, smart, reliable and effective cleaning machines. That is of course, except for the S9.
The S9 cannot navigate. Simply cannot. Meaning the 'secret sauce' that sets iRobot apart, is absent in this model, effectively making it just a far more expensive alternative in the league of competitors out there, to iRobot's product line itself. I assume partially because of the drastic shape redesign (brushes moving to the front, a 'D' shape overall and an offset turning axis when compared to the centered axis of the 'O' shaped models iRobot is famous for.
I spent 6 months trying with my machine, ignoring the countless reviews around the internet talking about how the S9 just sits in one area, can't figure out how to get away from spinning around the same chair leg 20 times, takes a blocked-off route to a room time after time when an i7 or 980 easily maneuvers around it. I thought "eh, it's a newer robot, firmware updates will roll out and fix it" and mostly "these users are probably not techie at all, I bet they mapped their house terribly on the first run and have no idea how to update it", etc.
No. None of that is true. This robot is just incompetent. And it has such a wide variety of tricks up its sleeve to screw things up. Every single time it goes on a run, it's something new.
Takes the wrong route to a room (or a non-existent because a permanent wall is there)
Trips over, gets stuck on, and carries around cables deep into clear 'off limits' zones. This has led to a few spilled glasses, broken controllers, and stripped cables when I dare to trust my robot won't actually steer directly into areas I've tried to block off and mark off-limits in the app
Spends 5 seconds in a room, goes back to base and says 'clean'
Spends 30 minutes cleaning an adjacent room to the one you want cleaned, usually because it can't navigate through a 3ft wide doorway (you can watch it hit one side of the doorway, back out, then make a huge arc to the other side of the doorway... or make a beeline straight for the open doorway, and at the last second either turn back around or veer left or right into the doorway, bumping in and confusing itself)
Never, ever updates its cleaning map even if it's been in a new room that it didn't originally map a dozen times.
Loses connectivity to wifi whenever you're juuuust too far away to conveniently troubleshoot it locally
Cleans a really random, out of the way part of a room in a quick row, and avoid the entire rest of the room's floorspace that you actually need cleaned
Spends hours and hours cleaning around an object or area during a full vacuum while the area you'd prefer to be cleaned is just a couple feet away- and many times it will NEVER get to it
Seemingly cleans AROUND dirty areas you wanted cleaned as you started the job. Now this is of course just a personal issue, there's nothing you can directly tie to the robot and say "you actively avoided the dirt here", but with my 3 other models, I was always, for 5+ years now, surprised and pleased when I came home and noticed all the spots I hoped it would get, were gotten. The S9 is the only model I've ever had where I can walk into the house and still see piles of dirt or hair exactly where they were before I left. Many, many times.
Another personal, non-technically-S9's-direct-fault, issue- but it seems the second I get in my car or leave the house, even if it's been cleaning successfully for 30 minutes or an hour already, I will get a notification saying "Roomba ran into an error", either a jammed brush or a cable got wrapped up or a 'cliff sensor' was blocked or it couldn't find its way home or got stuck like some kind of robotic contortionist between the legs of a chair, time after time after time.
I can't stand this machine. It's as close as inanimate objects can get to cursed. The programming seems to almost be written maliciously in this vacuum. This is the Windows Vista of iRobot's product line.
Let me explain myself for a second too, just so you don't think I'm quick to shoo off burgeoning tech. My entire life is bleeding edge and always has been. Beta testing, closed alpha's, developer programs, I am the first guy to jump on board 100% of the time. And it takes a LOT for me to get fed up with a buggy piece of tech, because I know exactly how tough it is to iron out bugs and the process involved behind it. But some programs and devices really just shouldn't be released in the first place, especially as 'final products' when they are.
The S9 has totally solid hardware, its design is robust and sturdy, it has all the hardware on board to be top notch. But the software it's paired with makes it a dud. Similar to Logitech products like TV remotes. Ever tried out a Harmony hub/remote? Beautiful piece of hardware, with broken, WIndows 98 era software that destroys the whole user experience and relegates the hardware to becoming a neat looking doodad on your coffee table that you'll never use. This is that in vacuum form.
But Logitech is known for pairing great hardware with awful, crippling bloatware. iRobot though, the software's the whole success story! What happened here, with this one model? I suppose the Braava 380t is a model that's also famous for awful navigation come to think of it though, so I suppose this isn't an isolated incident. It's just such a shame this product is unusable.
Back to my Windows Vista comparison I mentioned a few paragraphs ago. The S9 is truly, Vista. I upgraded my OS the first day it was available, beyond excited for all the cool new features and that sleek new UI it was bringing to the table. I even had a Windows Mobile 5 phone I was so eager to upgrade to a new HTC model with WM6 for. And I spent 9 months with both OS's (Vista and WM6), completely entrenched, totally dedicated to getting the hang of it all (as sometimes the hate for new software is just the learning curve). And I downgraded back to Windows XP by the 9th month. The experience was beyond atrocious, nothing worked, no menus were anywhere you remember them, compatibility was all over the place, some features were untouched, many were totally overhauled in the worst way possible. The biggest reason I wanted to upgraded past the new UI was DirectX 10 (Halo 2 PC and Bioshock both 'boasted' DX10 features as killer apps for Vista). Even THAT was totally not worth it. Games weren't stable, DX10 features were almost unnoticeable anyway, just such a total lost opportunity.
Then Windows 7 came out, becoming the new classic that did everything Vista tried to do, right. Truly one of the best operating systems of all time. So that's the explanation for iRobot and Microsoft's comparison. An absolute waste of an implementation, after some pretty good successes, and hopefully to be followed up by a perfected version of the first attempt. Plus, on the Microsoft track, Vista was only one in a long history of Microsoft's giant failures. I liken it to the 'tick tock' Intel generation moniker, but every 'tick' is a total failure, and every 'tock' is revolutionary. For example, Windows 98=solid, WinME=dud, WinXP=legend, WinVista=joke, Win7=masterpiece, Win8=garbage, Win10=revolutionary... we'll see what comes next now that we're in a more fluid, internet+subscription based era.
Hopefully we'll see the S9 as a simple hiccup in iRobot's impressive lineage. But in the meantime, DO NOT GET THIS ROOMBA. Go for the i7+ (or Costco i8+/Amazon i6+, they're all the same model with a different faceplate) instead!