As to combat, is it dependent on the player's reflexes or on the in-game statistics of the character or on both?
Ouch - dialogue used to be one of BioWare's strong points. Hopefully, this will not carry through to other BioWare games, such as Dragon Age.
The combat is dependent on both player skills and character stats .
As for the dialogue, I think the crappiness derives mostly from the fact that they voice all of the main character's lines, both male and female. Due to this, Bioware was forced to reduce PC's lines to a minimum, which turns the "conversations" into idiotic interrogations where most of the player's lines are a variation of "Tell me about whatever", with the NPCs unloading info on the player as mechanically as possible. It's the kind of design decision Bioware has been making more and more.
As Dragon Age won't have voiced PC lines, I'm hoping Bioware won't screw it up all over again.