That's my "problem" (for lack of a less dramatic word). I think hulking the lizard out like that was/is a cop out. I'd like to think there are far more dramatic and creative ways to make the lizard a supremely threatening villain than to simply make him so outrageously massive. Looking at the shot of the lizard and spidey crashing into the water...the size difference looks comical, not threatening. It's just another instance where I feel like they should have spent more time conceptualizing the lizard.
But, it's all moot; we won't know exactly how good the lizard will/won't be until the movie arrives, so while I have my thoughts on the matter at present, I'm waiting to actually come to a conclusion.