At this juncture based on all rumors to be correct I am going to say no...
Normally I always upgrade, and if not for the body and charging port change I would have upgraded.
The current iPhone 4S works perfectly for me 99% of the time, I have no real issues or complaints. I am beta testing iOS 6 (beta 3) and for the most part the changes I was hoping for are in the iOS and not the phone. iPhone 4S will run almost everything the same with the new iOS 6.0 full release.
The new iPhone (5) for lack of a final name, is not that different. OK, we have a few chip changes, faster, more memory, more storage and the Near Field stuff... all cool, but I can live w/o the Near Field for now, not sure if I would be using it anyway.
The killer for me, is the body change and the port change.
I have a LOT invested in cases, docks, charging cables, belt clips, Otter Box, etc.. to be tossing it all away to start over for changes that are not that huge.
So for me, unless I am missing something HUGE I can't justify the upgrade even though my GEEK status almost demands that I make the upgrade.
Only thing at this point that may change my mind is if my wife decides does does want my iPhone 4S I may do the 5 upgrade, or just get her a 4S when everyone dumps theirs to get the iPhoine 5.
So for now... Nope.. (sad to say)