Of course, what I really should've said was, "wouldn't it suck if we had Illidan at 12% and everyone decided to forget about parasites because 'omg he's trapped, burn!!'?"
It's a very good fight though -- Quigon, if you like Kael, you'll definitely enjoy Illidan.
Any fight that takes 1-2 nights to learn, but is repeatable through execution is generally good (hell it could take 1-2 weeks).
I've heard though that too much of the difficulty of illidan is placed on the shoulders of a few tanks in phase 2. Perhaps this is wrong.