As a former owner of an iRobot Roomba 581 I am absolutely delighted with the LG HomBot.
The HomBot working smart, not "at random" from the premises. Additional accessories (signs) as the Roomba is not necessary.
Collisions with objects are very rare (when Roomba is part of the concept that Thunders partially correct to around standing).
The Roomba was so uncomfortably loud that I have only ever turned on him before I leave the apartment. The HomBot is very quiet for a vacuum cleaner, it hardly disturbs. This allows also the lack of programming ability cope well, you can make him work while one is present, even with telephone calls, there were no complaints from the other party.
The dust container is large and easy to clean, the mop top, a not to be underestimated feature (so he can get even the finest dust even from the floor - and you can see the two supplied essays easily in the washing machine to wash (at max 40 °)..
One shortcoming that still have to be addressed: There is no provision that allows the user to replace the device's battery even / may (when the Roomba goes smoothly, replacement batteries there anywhere at reasonable prices).
Each battery makes flabby times ..
In which case even a (half) plus the HomBot goes, because he has a lithium-ion battery, the Roomba a NiMH battery.
The differences according to Google are on the one hand, that a longer life expectancy, a Li-Ion battery than a NiMH battery and that there probably is no or only very small Selbstendladung with a Li-Ion battery. (In the example, Roomba instructions is strongly recommended to remove the battery you should längerere time travel).
I would buy the HomBot (despite the high price) at any time and can recommend it with a clear conscience!
Correction from 15.1.2012: The battery can be quite easy swap. It is a Torx (T20) screwdriver needed with internal bore, the battery is mounted in the underbody with two such screws. It remains to be seen whether you can get the spare parts at reasonable prices.