1) It might just be me, but does it look like they were taken down and killed rather too easily? When I think of dragons, I think of grand encounters equal to the myriad minibosses of Morrowind (for my money there is a good chance that they are the Jills of Akatosh, that is lesser Aedra). Yet they are brought to the ground by a few spells and then finished by a few whacks of an axe, neither of which look particularly high-level. http://www.youtube.com/watch?v=K9hJMxw126A is a good display of this - Stormcall and two hits with an axe kills it.
2) Will they make traditional pure warriors totally obsolete? What is a sword or axe-wielding warrior supposed to do when confronted with a flying enemy? Even cliffracers from Morrowind (who ironically drove the dragons from old Resdayn) needed to come into melee range to attack, and the only 'flying' enemy from Oblivion were pathetic imps. Yet dragons, as we all know, breath fire - a ranged attack. For mages and rogues ranged attacks, which stop dragons from flying, are no problem. Will warriors be forced into a hybrid build to deal with the flying menaces? Or will dragons stupidly linger in melee range, out of character for creatures of intelligence, with their own language and agenda.
Of course, I judge based on gameplay footage seen so far, which may not be necessarily all that accurate of our experiences. I have faith in Bethesda to deliver a balanced experience, but for the time being I think these are valid concerns.