Since you mention the Roomba, can you give us a review? Reviewing sites are notoriously bogus, while you can be trusted! I know it's way off topic, but the Roomba may effectively perform a service that has plagued Man (or at least his wife's) for eternity!
I'm probably not the best person to do so, as I don't have it setup to run regularly (like you normally would). I generally launch it right before I leave the house, so it can take care of my kitchen while I'm away. I'm quite sensitive to noise, so I appreciate being able to have it clean things while I'm out.
I only have a 870, which is a fairly "dumb" model (it doesn't do any mapping, unlike the newer 900 or i-series). So, it just blindly bumps into things until it decides it had enough, and moves back to its base station. It gets the job done for me, and since it's easier to launch it than to get out the vacuum cleaner from the laundry room, it means I tend to run it more often than when I was manually vacuuming.
I'd say if you can afford it, it's certainly a time-saver, especially if you are lazy like me. I recommend going for a mid or high-end model tho if you can afford it. You will keep it for many years, and the newer 900/i series are certainly better than the 800 series (Wifi-enabled) or the cheaper 600-series (which might not be as efficient at cleaning up). Older models had slightly weaker suction, and they often use brushes that might require a lot of manual maintenance if you have pets or someone like me who loses his hair.
If the randomness of Roomba annoys you, check out some of their competitors, which are often smarter, but may also not be as efficient at cleaning. It's also very easy to find Roomba accessories (I go with third party accessories, which are a fraction of the cost of the original Roomba ones). Be warned however that some devices cannot work in the dark, while others do. So if you want one to clean up the basement at night, make sure it can work in the dark.
And don't expect one Roomba to take care of your whole house, unless you want to see it wandering around for 60-90 minutes at a time. Personally I fence it off to remain in the kitchen, and manually move it to other rooms when I want to clean these. My average-sized kitchen takes between 20 and 40 minutes, depending on the random factor, or how much dirt there is. Some people get a high-end model to cover their main rooms, and get a cheaper model to handle the basement where there might not be as much cleanup required.
Note that the Roomba mobile software is a bit quirky. I have never been able to make it register on my phone using the regular procedure - I have to reset the Roomba in the middle of the process for it to be seen by my phone, and finally added. I'm also unable to add it to a second device (like my tablet) due to this discovery issue. I have no idea how their discovery process works, but since it's the only thing failing at discovery on my LAN, I put it on account of just poor software.
