timppu: The only real complaint I had for BG2 was how many encounters were against some damn powerful demi-lich or something that had instant kill spells or something, or vampires giving you some quite serious handicaps. Meaning that you always had to carefully prepare for those encounters well beforehand, having memorized just the right spells and wearing just the right armor and weapons for that encounter.
That's why I liked e.g. Icewind Dale combat more, it was more "generic" so you didn't have to take ages to prepare for each encounter. Ok so maybe some other spell would have been even more useful against those IWD enemies, but your current spells and weapons still do damage to them as well. BG2 seemed to have much more encounters where your currently selected spells or weapons couldn't do jack shit.
That is a complaint of mine vis a vis the combat in BG2: the need to buff for so many different possibilities, which exhausts your supply of memorized spells, which then means you need afterward to find a place where you're allowed to sleep in order to have the spells available for the next encounter. At the end of the game where you're no longer allowed to sleep to recover ~ short of the workaround dtgreene mentioned and maybe a couple places I missed ~ those opportunities to rest are all-but-gone.
That's a big reason why I preferred BG. Yes, as the first title it had shortcomings that were later adjusted. But you also didn't need to spend 2/3 or more of your spellcasters' abilities on preparing your own crew and then debuffing the enemy - you could generally get straight to the fun part of actual combat except for some of the 'boss'-type battles sprinkled throughout the game. And you could take on several encounters before essentially being forced to rest.
Again, I may just suck at BG2, but I was actually getting tired of the game before that combat change near the end. Might have something to do with playing the two games back-to-back. Near the end, my "Aw, screw it" button had been pushed in and locked down. CTRL-Y, CTRL-Y, CTRL-Y....