It may reduce load times slightly but as for playing "smoother", I'm not seeing it. My son's box dual boots from HD (Barracuda XT) and SSD (550 MBps) ..... putting various games on both HD and SSD, I've played loading the game from each and, subjectively at least, there's no visual difference.
It does boot 5.6 seconds faster from the SSD (15.6 versus 21.2). Where you are likely to see a difference is in loading times during initial game load and and when moving from region to region in a MMO or loading a new chapter in a game.