I've only played the demo, but it's pretty fun. Check gamespot.com for a review, they're pretty accurate.
I own Splinter Cell. Its a damn good game, but it gets pretty impossible the farther you get. That oilrig level, ugh! Its a level in itself going through that obstacle course of poles to get into the damn thing. And the Chinese Embassy! You can't kill anyone.
I have SOCOM, and I'm on the same level you guys are. For some reason I can never get past getting the first hostage before the Riddah Rogue either take me out or the ambassador out.