So you don't know anything about it but you *do* know that someone shouldn't have spent so much time on some aspect of it, or that the entire thing could have been done much quicker. Okay, you've got your opinion and I'm not going to change it so why bother. However...
You have played it, right? But back again at the "I don't know anything about... BUT..."; look, fine, you think it shouldn't have taken years to achieve.
Define mechanics. I mean there's even a blog post about how they changed the combat damage so it's not just random but uses physics to determine the damages (velocity, mass, rotational forces etc? Been a while since I read it). So do you just mean "the fight feels the same so nothing else has obviously changed". Refer you back to the blogs.
If you're honestly of the belief that work is only worthwhile if you see some massive difference, then would question why you ever bought it in the first place. The method of fighting wasn't going to change... the style of game play wasn't (overall) going to change.
If you *honestly* think it is no different, and you've played, then .. well that's where you're at. Fair enough.