Big hits in our house has been skylanders (dd1 had to be dragged off the Wii), Furby and good old lego.
Disapointing items were the addictaball (should be called impossaball), its a pile of cr*p and a bit broke off after 5 minutes of trying to work it out, Hello Kitty cool cardz, probably as dd2 is a bit young for it so just chucked all the bits everywhere without reading the instructions.