He's great in rom-coms, terrible in everything else. Green Lantern (or wolverin origins, blade 3 if you like), is all that really needs to be said about his superhero resume
I actually really enjoyed him in Wolverine when he was just Wade Wilson, and I think he's going to bring the same kind of energy to the Deadpool film, but probably even more spastic. Never saw Blade 3 (though I want to), and I thought he was decent in GL. I definitely wouldn't say he's great in rom-coms, and terrible in everything else. Ever see Buried? I thought he was superb in that movie.
I urge everyone to wait until they've seen Deadpool to judge RR in the part. From everything I've heard from my colleagues working on the movie, he's an absolute star in the role.
I honestly wouldn't want anyone else to play Deadpool. I think Reynolds to Deadpool is Jackman to Wolverine. If you ask me, Reynolds already nailed it in the cgi teaser/promo.