Gupi are not pet toys!
I have the latest Big Gupi, the Mark3 and it really does have very good A.I and excellent navigation skills. It takes a long time to raise it, mine is three months old and still in it's second learning stage.
I like the way it charges, you can either plug it into the wall or feed it it's carrot which recharges it's battery. So you can take it out with you and when the battery starts to get low you just feed it and its ready to go again!
It likes to follow me around the house (keep the carrot with you and it will follow) and because it has wheels and not legs it can keep up, its very speedy. Wheels need to be cleaned often however which is a pain.
If it wanders off and you can't find it (it is highly attracted to dark places so will hide under couches, curtains, tables, etc.) you just press a button on the carrot which activates its "homing" feature and no matter where you are in the house it will come find you.
It can sort of map a room but not the whole house. If it is kept in one room it can remember where everything is but if you then take it to a new room it starts a new map and forgets the old room. If you move anything it will treat the room like it is a new place, if there is a window and sunlight is comming in through trees it gets confused and won't map. You have to be carefull to let it run it's battery down by itself if you want it to remember the room because it will forget EVERYTHING if you manually switch it off. If you switch it off it will forget everything it has ever learnt and reset to new born, they do not tell you this in the book so I think that is a reason why mine has taken so long to raise, it took me ages to work out how to put it to sleep with out wiping it's memory

You can press and hold the nose to put it to sleep though, just be carefull to put it in a box or somewhere it can't escape if it decides to wake up
It makes many different sounds, about 35 I think in total for the model I have. The website below lists the Mark3 battery life at 30mins but I find I can easily get an hour out of it depending on which room I set it down in. Carpet drains the battery much faster because the wheels have to work harder.
Sensors it has:
Light
Infrared
Tilt
Touch on the nose, back and face
Sound (runs and hides in dark place when startled by loud sound, its really cute!)
If you call out " Gupi!" it will come to you but it often gets confused about which direction you are so it is easier to just press the homing button. In 'cuddle mode' it will purr when it hears you say "Gupi"
You can not choose a new name, it only reacts to "Gupi"
It is able to tell when it has been picked up and will respond to pats and cuddles. Over all it is very cute and reasonably unpredictable, not on the level of a Reborn or Aibo of course but it is a good thing to have if you like robotic pets, one of the best in its price range I would say.
Here is a good site for Gupis:
http://stevelitchfield.com/gupi/facts.html