Pocket Gamer: Skylanders Lost Islands on iOS is brilliant. It's a delightful freemium world-builder that plays about with the licence, rewards you tremendously, and throws a cheeky wink your way every so often thanks to a decent sense of humour.
If you want a portable Skylanders experience, that's the one to go for, as Skylanders Giants for 3DS is entirely skippable. It's a significantly compromised, stripped back pseudo-version of the home console adventure, and one that only Skylanders die-hards should bother looking into. 5/10