Well, if you're seeing this, you made it! :D Shiny huh? :P
So, wondering what's different? Poke around~ Hopefully everything should be self-explanatory, but if you have any questions ask here. :)
There are a few differences that you do need to know about, though.
1) No more HTML allowed in posts. At all. This mostly affects people using the <center> tag - it doesn't work anymore. Please use [center] or [align=center]. If you see any stray bbcode lying around in your posts (bbcode that is showing as text and not doing things), just go to Edit the post, then submit it again. It should reparse the bbcode and bring the post's display to normal again.
2) If you have a rotating avatar which rotates between avatars of different sizes, some of them will be stretched and some will be squished, to fit a common size. I'm sorry but I can't disable this. :S Best to just resize them all to the same size, they'll work fine that way (I'm in this boat too, so..)
3) Some posts might have gotten some weird characters introduced during the conversion to unicode. I tried to catch most of them (ahem, you people who write posts in Word ;P) but you might see an error here or there. With 100000+ posts it's impossible to expect every one to be perfect after all they've had done to them.
4) Most of you will have to either edit your signatures (I see a lot of <center>s in them) or just resave them. If you see bbcode that's just bbcode in your signature, go to your control panel -> profile -> signature, and hit Submit. It will reparse the bbcode and be back to normal.
5) If you see anything you shouldn't, any error, or are able to do anything you shouldn't, please please let us know. The conversion copied the permissions of what different users are allowed to do, but the new system is different and there may be inconsistencies.
Similar case for the KS system. I had to write most of it myself, since there was no version of it for this upgraded phbBB. If you get any errors with the KS, let me know here or in a PM.
Thankee-saaais, and welcome~ :DDD