Hrmm... well, the model itself is interesting - the detailing is kinda cool I guess but... I'm sorry...I just don't like it as a Sobek. And I know that that's not very constructive, and I know that it'll be seen as useless criticism, but honestly, that's my overall impression. I wouldn't say i hate it - there are lots of good bits - but the overall impression, notsomuch.
I think the main problem I have is that it loses what I see as the basic concept of the Sobek - a big, heavily armoured head and engineering section that overlays the tecchy bits underneath. I think the fins and the head should maintain their smooth, unbroken look, in order to imply that they're heavily armoured - as it stands, the layering reduces the impact of that significantly. Detailing and greebling can go nuts in the tecchy parts, but the armour should, IMO, remain very basic. Also, while I can see that you've tried to retain it, the funny U/V shape on the top of the head is considerably diminished here, despite being one of the Sobeks most noticable features, and its no longer recessed into the armour, which seems like an odd decision.
I do like the engines up the front, and as has been mentioned having them exposed is implied by the original model.
The rear, it's not so bad - I can't honestly say I like the wheels, though that's probably going to be a person to person thing. Again though, the terraced armour plates on the projecting fins look wrong - should be retained as solid IMO. The neck is interesting, quite decent actually, no complaints there.
Yeah, so for me, the head and tailfins are the most problematic. Do with that what you will.