It is a console (not a computer) that you buy cartridge games for - usually it comes with a single game. The standard one used to be Winnie the Pooh, but I believe you can get different ones, like Dora the Explorer. You really need to buy the separate mains adaptor for £6, it doesn't come with it(!) because otherwise it's very expensive in batteries. The pocket vtech take the same games and dh thinks you can play these through the tv.
Ds has one (3.8yrs) and his favourite is Bob the Builder. He occasionally plays Thomas, but hasn't yet played Toy Story which he got for Xmas. Wouldn't recommend Noddy.
I bought one as a present last yr from Boots for £25.