I've just recently got a blu-ray. The first films i got were Pred 1 & 2, and AVP 1 & 2. As has been said, Pred 1 was a bit of a let down, but the picture and sound quality made up for the lack of extras. Pred 2 was much better extras-wise. Although I would have liked them to have been available in 16:9, or widescreen. Also AVP-2 does'nt have the extra footage, mine is only available in the cinema version which is a bit of a downer. But all in all I'm happy!
I also recently bought a Blu-Ray player and I was going to buy P1 and P2 but decided not to because of the reviews i've been hearing about them. I'm happy with the DVD versions, I wont re-buy these two on Blue any time soon, unless they release another version of the movies with more extras we have not seen before. Or if it comes bundled with a collectible etc. But I'll buy AVPR on blu-ray though in a few weeks.