Couple of things. Most recently Just Cause 2. Played it for a bit and was pretty bored with it. Came back a few months later because I was bored, started exploring the island and just screwing around, and my gods, it was awesome.
A lot of RPG's are also kinda 'meh' to me when I make my first character, because that's usually screwing around and figuring out what's what in the game. Then I usually make a second character and love it, or at least like it enough to finish it. This happened to Dragon Age: Origins, Dragon Age 2, Planescape: Torment, the original Fallout and Oblivion.
Deus Ex was also pretty 'meh' the first time I played it. What can I say, in some respects it has aged rather poorly.