[Klashikari]

Pretty much liked Konata&Kagami duo. (the harmony between them is just too good... konata giving punch lines for kagami wins)

the amount of puns, easter eggs etc is pretty large, but the pace is really fluent ^^

as for the ED, fankly, i disliked it for 2 reasons :
-just like vexx said, the fact Hirano-san blurt her "serious" voice out of the blue is something really weird, and doesn't really suit the scene.
-While i'm a big fan of her voice, i just thought that she doesn't fit the style of the song at all. (i didn't feel any smooth feeling and such).

Perhaps i'm too conservative, but i couldn't really appreciate the tunes she gave for "sore ga ai deshou". (and i don't think the "karaoke effect" would be the reason, it is the voice, nothing else)
and before you ask : i'm a big fan of the original OP.