In terms of the Scooba's value, if you have good sized swaths of hardwood or tile that you can clear off for it, it becomes a practical alternative to most mop work. However, I wouldn't recommend it for the non-technical--I had to clear the pump opening a couple times by forcing water through it (per tech support). Still, I hate mopping, and it was decent enough at it.
In terms of practicality the Scooba is like the dishwasher-convenience paradigm. You maintain it, load and unload, but it saves you work overall. I get the sense that the return on effort is slightly lower than the Roomba.
After we had our first child, we started having a person come in and clean and although it isn't cheap, it is probably the change that has made the biggest improvement in our quality of life in a while.