The GPS is most certainly wonky. I don't know about "slower", but it drifts around a lot more, seems to keep moving for a bit after I stop, etc. I know of at least one other person with an S3 who appears to have more complaints than I did about this update, though. I'm rocking the oh-so-powerful HTC Thunderbolt! Feel the fury, baby!
There have been a few improvements. Selecting a key while making a link is nowhere near as horrible an experience as it once was. The portal submission tool is very nice. Overall the app feels less laggy, as has been true with most of the updates.
If I leave the app and go back, I'll occasionally get a lockup followed by a "stopped responding" force close. But that's been pretty much true all along.
Did you try a "clear app data" from application management? I find that I need to do that at least every couple of weeks or the app gets a whole lot less stable. The occasional degunkification seems to help a lot.
Facebook
Twitter
Instagram