Only the loss of spell crafting. Every character I made for Oblivion always ended up with TONS of custom spells, but then again, there was no (easy) way to delete them, and it did get a tad cumbersome.
Still, I know why they must have done it. It was easy to exploit. You could chain-cast a series of spells to buff yourself up to higher and higher levels of magicka until you could cast custom spells that should have been impossible for anyone to cast. (Think maximum damage + maximum area of effect, "I win" button). You could make a "training" spell for each school of magic that cost so little magicka that you could put a weight on the keyboard and leave the room, and when you came back, your skill had hit the next 25-point plateau. That's how I always raised my magic skills, lol. Took way too long the normal way IMHO, at least when compared with other skills. You could cast a disintegrate armor spell on yourself and then power-level your smithing skill, etc.
Just too many exploits, and the spell book always ended up hopelessly cluttered, so... I get it. I'm a sad panda, but I get it.
Everything else I've seen and heard so far = spot on. I loved Arena, I loved Daggerfall (despite the bugs, lol), I loved Morrowind, I loved Oblivion, I loved Fallout 3, and I will love this. For that matter, I loved Terminator: Future Shock, and who else has even heard of that one?? But it was the usual Bethesda experience: amazingly ambitious, buggy as all get-out, made every other game look flat and boring by comparison. They're all different games, but each one redefined the gaming landscape and raised the bar for the entire industry when it came out. Bethesda have never let me down, they're the best in the business. I think their design philosophy could best be stated "Shoot for the moon... even if you miss, you'll wind up among the stars." So we get a few bugs, some strange design decisions (like being able to carry around a full-size sailing vessel in your pocket in Morrowind, or was that Daggerfall?), and, in the bargain, the best video games ever made.
Thank you for posting such a positive thread, BTW. I grow weary of the whining.