I consider Oblivion to be a great triumph ... as a tech demo/infomercial of Havok, facegen, speedtree, net immerse engine, whatever the hell it was they used for terrain erosion effects, overhype of a pathetic set of scripts pawned off as AI, and destroying egos CPUs and GPUs everywhere. As a RPG I consider it to be a complete and total failure. (i.e. the game itself feels like an afterthought to playing with their new toys... too bad that they used their flagship product to experiment with...)
As a matter of fact I found most of Oblivion so uninteresting that I have no interest whatsoever in any expansions or any other "RPG" produced by Betheseda until they can concretely demonstrate that they have learned their lesson and can produce decent RPG fare again. I guess it's no wonder that one of the two main designers of MW quit Bethesda as soon as Oblivion shipped, and whose comments wrt Oblivion, if read correctly, foreshadow this conclusion. Bottomline though, in reality, is that they've made so much $$$ off Oblivion that their pinhead suits will probably think it was the greatest game ever, and that they need to make alot more just like it, preferably with a 10h $50 part and c. 100 $2.50 addons. I'd never thought I'd say this, but I really hope that Gothic 3 turns out to be really open ended(2 felt like an adventure game with more than the usual amt of RPGishness and action fighting), and kicks the crap out Oblivion.
In any event, I've ended up going back to MW + MGE + other mods, and find myself actually enjoying/appreciating that game more than ever.
Mitigating circumstances: Yes some of the annoyances, the dumbing down wrt quest GPS, etc. can be SOMEWHAT mitigated through use of your own or other's mods, however, I personally, prefer to have that sort of option out of the box. Also, I DID enjoy certain aspects for a while, e.g. sneaking around hunting various wildlife, etc.
Lastly, my machine is quite capable of running this game at an adequate fps/detail(high, 1280x1024(max monitor)) so it is not about poor performance of the technologies, etc.