I think you all approach this from 2 extremes, either that he's realllly talented (AEK66) or completely useless (DUDE).
Admittedly I'm not a big fan of his and I don't think he can just bulk-up, he's got a naturally small frame and however much he works out he'll always be weak (relative to other pro-athletes that he competes against), yes he may improve slighlty, but nothing too drastic.
On the other hand, he's not completely useless. He's better than Tumer, Koke and Radzinski re DUDE, don't undermine the kid too much.
As for Crouch, he's not great at heading but he's great at jumping. As since people seem to like talking about championship manager on here :P he might be rated 20 (the max) for jumping, and a 15 for heading. But if that's the case Samaras would be a 15 for jumping and and 13 for heading. He's tall but he doesn't make runs ahead of the defender for example. Samaras never meets the ball, he jumps up, if it hits him on the head then so be it.
Look how in of none of these Shearer headers does he out-muscle a defender, yet Samaras wouldn't have scored any of them. It's because he doesn't have the explosion nor tactical know-how, to make that last second explosive sprint to get ahead of the defender:
http://www.youtube.com/watch?v=EoYI2A0FJdg (sorry for not puting the video up directly, i don't know how to do it). - Note by moderator: Instructions on how to post YouTube Movies have been posted here
So he's not just weak but lethargic and although he can't bulk-up too much he can work on explosive-cardiovascular training combined with tactical running. But it's up to him or his coaches to identify that. Therefore in my humble opinion AEK66 is overrating him and AEKROSSOPONTI is way off when saying he'd be one of the best in Greece. But DUDE is also overlooking his potential, he's potentially a very good forward and has more potential than many other Greek forwards who might currently be better than him, like Choutos or Salpiggidis for instance. Whether he fulfils that potential is a different matter because we've been talking this kid up for a while and he isn't progressing at an acceptable rate, but he can do it if he has the right people around him.