The Nova Beam was wicked awesome, but you didn't get to use it nearly as much as I'd have hoped.
Beat it today, finally, after being distracted by a few other games. I gather that little "retrospective" bit before the credits was the 75%+ ending? Also, the 100% ending, soo not worthwhile. Pretty lame, I'd say. The whole Phaaze bit was pretty nifty though. Kinda cool mechanic they decided to introduce. Also, last boss[es] were good fun too.