My thoughts on ICQ 6 are that it's solid as a rock for me!
Hasn't crashed once... loads fast... responds faster ... it's overall a much better app.
I wont use Trillian or Miranda ... both those apps fail to grab every message that is sent ... I've tried them both multiple times and often there's been a drop in the comms when I've been using it.
ICQ 6 is pretty good
I'm happy with it now. Whereas, I HATED v5