Underrated:
Daniel Sturridge
Rickie Lambert
Jordan Rhodes
Edit (thought of more - a lot more apparently):
Demba Ba
James Mcclean
Stephane Sessegnon
Thomas Vermaelen
Vincent Kompany (I think anyway)
David Silva (He's good, but not as good as he is IRL)
Lionel Messi
Cristiano Ronaldo (Both he and Messi never, ever score as many goals in game as they do in real life)
Ezequiel Lavezzi
Michael Carrick
Luis Suarez (Pains me to say because I hate him)
Alex Chamberlain
Kieran Gibbs
Kyle Walker
Fraizer Campbell
Gareth Bale
Ryan Taylor
Micah Richards
Danny Welbeck
Michel Vorm
Ashley Young
Sebastian Larsson
Adam Johnson
Nathan Dyer
Joe Allen
Leon Britton (Better than Xavi IRL, apparently...)
Jordi Gomez
Neil Taylor
Grant Holt
Jack Colback
Craig Bellamy
Hatem Ben Arfa
I could keep adding names, and make a list just as long for over-rated players. Howver, as somebody else said, a lot (but certainly not all) attributes are pretty much correct for when they were actually implemented.