Chaos Theory is very fun on multiplayer. It solves some of the problems of PT's multiplayer by beefing up the mercs a bit (melee attack, camera network, etc.) while still adding new stuff to the spy's arsenal. Also, the map tutorials are great for newbies.
Also, I wouldn't call Splinter Cell a shooter in any case. Usually, you'll only enter firing mode when you're shooting out lights or when you're knocking out guards from a distance with sticky shockers/airfoils.
Overall, CT is pretty nice. Single player is fun, but a lot easier than the previous two, since you can easily knock out or kill a guard in one hit. Combine that with tricks such as bashing down doors, and you've got a pretty easy game on the default settings.