I havn't seen the directors cut but I've seen the original. The first time I saw it I was really confused, it took a second watching to fully understand it.
There's already been a thread about this (7 months and 5 days ago

) which can be found at
http://oddworldforums.net/showthread...t=Donnie+Darko so I'll just repost what I said in that thread

.
It is indeed a great film, a friend of mine has it on DVD and we've watched it a few times. When it ends it leaves you a lot to think about.