I'll second PDA games. It's port of the bonus levels from Alien Hominid on PS2 and definitely a fantastic little title. Catchy music, simple premise, almost more puzzle than platformer but is one of the few, the very very few, platformers that work well with touch controls. Also, Mutant Mudds. Free, not freemium, and stands as the best iOS platformer that imhave played. *Paper Momsters is currently free, so definitely try it out before making a purchase; I couldn't stand it.
Bloo kid 2 is a phenominal 2d side scrolling platformer! Raccoon Rising is an excellent Platformeresque adventure game. Super Lemonade Factory 1&2 not on anyone's list? Wha??? Paper Monsters is a gorgeous platformer very much worth playing. Also try... Supercow, Akane, J-Werewolf, Poly Roll, Random Heroes 1&2, Alex (Mayan Mysteries), Worm Run, Devious Dungeon, Knightmare Tower, 4NR, Robo Rush... All fun games as well!