I agree that the pistol in h2 was weaker than the original, but I didn't mind that so much, since it helped to improve overall game balance. In the original I almost always carried a pistol (unless i was fighting the flood), and i probably would have again in h2 if it wasn't for the lack of pistols to be found.
Battlerife *would* have been better with a selector, but iirc you can't dual wield the battle rifle like you can with the SMG, so it would have become too much of an 'everyman' weapon with that function. As it stands, i prefer the battle firle over the original assault rifle. General balance of weapons was right, in reference to the human guns. The covenenant guns... well i don't know what was going on there.
But my main gripe was an easy one: the story was weaker than my nanowrimo effort, and I've come up with that in the space of a month. Bungie had a lot longer than that.