I've had a little robot 3 for 5 years. It isn't the most reliable device in the world, but you learn very quickly all the little quirks of how to fix it when it breaks and it isn't too bad. I'm very, very happy with it. If you aren't handy then it might be more annoying for you.
My only complaints seemingly are fixed by the litter robot 4: better sensors (so it breaks less) and a larger poop storage. I would buy one immediately if I didn't already own the LR3.
I bought one years and years ago (when the 3 was brand new). I wouldn't recommend it, and have transitioned to a non-mechanical litter box. I would have said I liked it for the first nine months or so.
1. The mechanism is fairly finicky. Every 3 or 6 months it would jam, and require some debugging. It's mechanically not as simple as I would hope.
2. My cat developed a UTI, and it was hidden for longer than it should have been because I was not watching the litter box as closely as I would if it required more frequent cleanings.
3. After 16 months it developed a smell that was very hard to clean. I spent a week with it disassembled, washing the many bits and bobs, letting it dry and checking the results. It was broken into more than a dozen small pieces, but a few of the pieces were stubborn. Afterwards, it needed this deep cleaning about every 9-12 months. Traditional litter boxes can be cleaned very easily with hot soap and water. Traditional boxes require more frequent upkeep, but I find the task to be less stressful with very little cognitive load.
I got one about 6 weeks ago, and I've been really enjoying it so far.
We were trying to debug why one of our cats just won't poop in the box, and the LR4 hasn't fixed this entirely. She will pee in the box, but no matter the type/size/placement/robotness of any box she will almost always poop just outside of it. But our other cats use the LR4 and that's been wonderful.
I love my Litter Robot 3 but it gets stuck every once in a while which can create a mess if you don't notice it relatively quickly (occasionally the "poopie paw bandit" will strike and track litter all over the floors). I'd love to know if the Litter Robot 4 is more reliable.
I don’t own a robotic scooper, but a reservation might be your cat’s health. Since they tend to hide their illnesses well, a change in your cat’s litter appearance or habits can be one of the only signs they’ll give you that they’re sick. You could easily miss that with an automatic scooper.
I haven't had mine that long, so I can't speak to the long-term issues already reported in replies to your comment.
But overall, it seems worth it so far. My partner and I put off buying an automatic box for years because of sticker shock, and I'm glad we finally got one.
My cat has no problem going inside the robot, but he gets scared when it rotates. The result was that he clawed all the buttons (and the faceplate) off the control panel.