I recently started using my (comparatively old) Roomba again, and I've been reminded of my chief complaint about Roomba: it gets dirty and needs to be cleaned.
Our house is a regular petting zoo, so stuff accumulates pretty quickly. This fills up the bin, which isn't so bad because emptying the bin is quick and easy. But the human hair and pet fur fowls the brush, and that takes some serious effort to clean. I suppose the Roomba for pets (which appears to be discontinued) addresses this with a brush that is comparatively easy to clean.
And then last night I discovered a new place to clean: the side sweeper brush. That thing was totally fowled (not surprising considering I just discovered that I needed to clean it - "read all the words"), and it took me 10 to 15 minutes with my pocket knife and tweezers.
I find it ironic that a cleaning tool requires a non-trivial amount of cleaning. Perhaps if I kept up with regular vacuuming, Roomba wouldn't get so overwhelmed by crap.
Finally, the reason I'm just getting back to using Roomba is that I just got a new battery after killing the old one some time ago. It turns out managing batteries with Roomba is a bit different than other devices I've used. Typically, I run devices down and recharge them. If I don't have an immediate use, I'd leave the device uncharged. Well, Roomba keeps discharging the battery even if it's not in use. And if you do that to a battery that's already low, it deeply discharges the battery - definitely not A Good Thing. I noticed the discharging thing: sometimes when I'd charge the battery and not use Roomba immediately, the battery would be low when I went to use it. So, Roomba prefers being left on the charger, even if you're not using it, which is something I tend to avoid with other devices. Anyway, the result was that I only got ~50 cycles out of the original battery - not good. The recording on Roomba's tech support tells you if you're not using the unit anytime soon, you should take the battery out. Fortunately, it's easy to install and remove the battery - e.g., no screws required.
Don't get me wrong: Roomba is still fun to use, and I did just put down more money for a new battery. So, I will continue to use it. It's just not as carefree and easy as I'd like to see it.