I got a Roomba from my parents this year for my birthday. A pretty cool because it cleans alone and charges itself again,the only problem is that it needs free space to move around. So cleaning up before is a must so he doesn't get stuck. Also the corners are not so great. It's good for making the first sweep.
Can you share videos of how it works for you mate? because i think we have the same house position and i am planning to have robot as well.
so Please if you don't mind me sharing then i will be very glad.
YouTube is full of such videos. Every small right angled shaped place will be the hardest place to clean for Roomba. With its little broom, it can just get the farthest corner. Roomba either will clean it for few seconds and drive away, or will stuck there for minutes trying to get a better trajectory to get out.
Roomba is good in the place where you have lots of open space and don't have furniture. Or for a place that was cleaned 1-2 days ago. He is a perfect "pre-cleaner", but it can never replace a cheapest vacuum cleaner.