There's no question that movieverse Iceman is lacking a sense of humor. But that's not his only characteristic. Anyone who thinks that he's just "the class clown" is obviously not basing that opinion off of comic canon. Read Giant-Size X-Men #1 and tell me you don't see the angry, more serious side of Bobby Drake. Look at the icy (pardon the pun) attitude he has towards Wolverine in the movies and compare it to how he received his new teammates in Giant-Sized. Read any Adjectiveless/Uncanny issue he was in from the last decade or so and tell me how happy-go-lucky he's been.
Am I saying the film adaption was great? No. Was he butchered? I don't believe so.