My biggest concern is the random guest thing. I imagine all quests relating to the various storylines will be set in stone, but will all side quests be random? Don't get me wrong I think it is a cool idea but I'm a bit concerned that some of the randomness might bite us in the ass. What if for one quest I was going to be sent to some HUGE ruin filled with all sorts of goodies, but since I had been to that ruin before I get sent to some dinky cave with little to no good loot? I'd like side quests to be different from random quests. Have the storyline set in stone, side quests set in stone, and random quests be the lowest tier of quests to undertake (not meaning they aren't as fun, just that they aren't as frequent).
Also, I found the number of cities to be quite alarming. There should be eight cities, there are eight on the map, EIGHT! I suppose that after 200 years three cities could have been destroyed but I still feel like five is too few, unless each of them is no smaller than the Imperial City was. I think a lot of the believability in Morrowind came from it's vast amount of cities and settlements. There had better be A LOT of small villages and settlements dotting the map.
And perks?!?! Really? It isn't necessarily a bad thing since they were included in Oblivion, but I don't know about the whole Fallout style they're implementing. I'm somewhat of a completionist (not a real word I know) when it comes to TES games, and I'd be a little sad if I couldn't get every perk available (you can in Oblivion).
And last but not least, I'm a little concerned about the sacking of the Major/Minor skills, but this mainly stems from my lack of knowledge over the new system for leveling up.
All in all the pros outweigh the cons, if they can even be considered cons at all, and I'm really happy and excited with all of the new info.
Supposedly the cities a very large, possibly larger than the imperial city? Also this is just speculation but, there may be no more compartmentalization of the world or if there is there will be minor compartmentalization. The reason I say this is because Bethesda is now using Id Tech game engine (just guessing since they bought up Id software) instead of Glitchbryo. This will most likely allow them to make the world far more whole and open.