Alot of these 'problems' people run into are because of the AD&D rules. The 2nd edition rules have been around A LONG TIME and are balanced out appropriately, the rules are as they were meant to be and Black Isle has done an EXCELLENT job of implementing the rules and an engine that can take expansions (kits, 3rd edition rules, etc). Now they had some initial struggles with it, but I think they finally have it complete in BG2's engine. The IWD engine uses their older 'kludge', 'dual wielding bonus for rangers = +1 attack/round'. I like the TRUE dual-wield and such in BG2 that allows you to use the damage and special abilities of the offhand weapon, with corresponding benefits/penalties. Overall I like the IWD+HoW engine better than the BG I engine, because it has some of the needed features like gem/potion/scroll bags. The downside is you don't get the exp bonus for picking locks (based on difficulty of the lock) or learning a new spell. Those are more true to the spirit of AD&D, though I think they over simplified it

Learning a spell should take days, not seconds

If they're gonna be true they should make you hole up in an inn for a few days to learn sll those spells and write them into your spell book.