I'm a huge fan of Splinter Cell on the XBox. When I heard it was coming out for the PS2, I grabbed a copy to see how they compared.
I was really disappointed with the lower quality and jaggedness. Splinter Cell on the XBox was amazingly smooth, and we played the game many, many times because it was so enjoyable. While playing the PS2 version might have been better graphic-wise than say a Bond game, it wasn't up to the XBox version's high quality.
The PS2 version promoted its "great new levels" and adjusted gameplay. So we started comparing. We found actually that many levels were missing many, many pieces. In the XBox a bad guy might have been standing against a balcony looking out over the city. In the PS2, he was standing against a flat wall! There were bad guys missing. There were puzzles missing. It felt "dumbed down" in many ways. Again, having enjoyed it so much on the XBox with its complexity, intricate graphics and challenging puzzles, it was extremely disappointing to keep hitting, again and again, a spot where a scene had been 'kiddiefied'.
They were stupid little changes, too. For example, in the XBox version, you're walking through a house and find a bathroom, with lots of detail. Up on the wall is a medicine chest, just like you'd expect. In the PS2 version, the bathroom is missing and you just find a health kit lying in the middle of the hallway. It took away a lot of the realism.
If you don't have an XBox, Splinter Cell is still a fun game and can give you enjoyment for many hours. I suppose if they tried to port Halo to the PS2 you might have the exact same problem - that a game that people LOVE on the XBox because of its giant levels, intricate graphics and complex gameplay would be reduced to tiny levels, jagged graphics and simple puzzles. Yes, it could still be fun. But it's sort of like listening to your favorite Rock Anthem through tinny speakers at a quiet volume, instead of blasting the sound through your high quality stereo.
For that same "quality level" experience on the PS2, I'd really stick to games where the PS2's abilities shine - which seem to be the Kingdom Hearts and Final Fantasy genre of games.
Buy Splinter Cell for the PS2 from Amazon.com