I started a new character (no DLC) and installed patch 1.9 (after removing patch 1.5) after reinstalling the game, and I've noticed several differences compared to my previous file on 1.5, both good and bad. Many, but not all, of the bugs are gone and the game (usually) runs smoothly. I've noticed that there is A LOT of minor stuttering that happens about few times every 5 minutes, even when I'm far away from large towns. I've also noticed that the game doesn't render too many background objects until you're pretty close by (I've seen NPC's and trees appear just 250 feet in front of me out of nowhere). The upside is that none of the stuttering is game breaking, and doesn't increase the longer I play or larger my save file gets. On my old file, the game ran smooth as silk until about 1.5 hours in when light to moderate lag kicked in.
Don't get me wrong, this game still plays MUCH better than at release, but there are improvements to be made. I'm new to this forum, but it looks like there are many people having problems with 1.9 with DLC's installed. There is a helpful guide on how to help reduce PS3 issues when playing Skyrim that has helped me keep lag and glitches to a minimum. Google "skyrim trouble shooting faq" and select the one that says it's made for the PS3 and written by someone with the username "VT-14."
Hope this helps!