Compared to the PC, the 360 doesn't have much power at all. Old technology vs. rapidly evolving, new technology.
Mind you, I'm not interested whatsoever in getting into a PC vs. Console debate.
The PC will always be far more open and mod-friendly than consoles. However, it's good of them to try and develop something console users can use to get mods to work. That's something I've really wanted to see. It will be interesting to see how Bethesda manages to implement it.
Third, the DLCs are of no concern to me.
Someone will find a way to make them work on the PC version. "Reverse engineering" might be against the license agreement, but a license agreement has never stopped anyone before. Even then, I doubt those DLCs will be completely exclusive, much like Apple's relationship with AT&T and the iPhone. They'll eventually be released for PC, likely on a disc similar to Oblivion's
Knights of the Nine. I don't put much stock in this "exclusive content" thing, obviously.
As far as menu system complaints are concerned, if you haven't used it, you have nothing to complain or compliment about. From what I saw in the videos, it looks pretty snazzy. Usability is another story entirely, and it will be interesting to see how useful those are on the PC.