And it's still lacking depth. To me it just seems like they've spent most of their time designing forgettable caves, ruins and oblivion gates. Isn't there over 100 oblivion gates and each one looks about the same?
No...
There is like 12-20 Oblivion gates with 8(?) different designs. Yes, they reused them, but what can you expect?
And the Oblivion gates dont look the same, they are all laid out differently, unless you mean they all look like a lavafilled hell, in which they are supposed to look like.
And its not lacking in depth at all. There is over 200 hours of gameplay, if that isnt enough for you then I dont know what is.