My boy of 9 has the last two Skylanders and wanted this one desperately (his words). He hasn't played the giants game as much as the first as he thought it two simple without enough levels, I was reluctant to buy this one but succumb to his pleading.
The big difference is the characters can be body swapped, legs and heads can be swapped so the skylander can perform different, i.e quick legs mean the character will move quicker, simple. Not all the characters that you buy are swappable, make sure you check before you buy the characters, they have swap on the box.
The bodies are connected by a magnet, very clever how the game knows what going on.
The game it self is pretty much the same as the last two installments, I liked the idea that the old Skylanders can be used on the game but they don't have the swap feature which will mean more characters being purchased, more figures sitting near the console and less money in my wallet.
My boy also has the Disney Infinity Starter Pack (PS3) which I personally prefer as you can identify with the characters, although Skylanders missions are far more challenging.
There is nothing not to like about swap force, its additive, fun, challenging, just a shame its going to cost me more money.