I agree with Siduri on points 1 (I miss my fat avatar) and 2 (it makes for extra mouse work to get to the most recent post in a thread). Point 3 I don't do it that way anyway, so, not an issue.
Getting used to the green, finally.
A really good thing is the extension of the mail boxes, for pms and outgoing pms etc.. Beforehand one had to pick and chose what to keep if your box got full, now I am niot sure there is even a limit - it's much better. And there's no pop up box depending on what platform or setup your computer has to ask "Would you like to open this in a new Screen?" (which never worked for me), or you had to press "Cancel" to open it in the current screen. Vast improvement on that now. Can just go straight to it. Good stuff
I hardly ever need to log in too - which is a bit confusing. Unless I empty my cache as a part of regular computer maintenance, it must look as if I am always there. Not having to click the "Remember Me" box is good though, so I don't get logged out after a period of inactiviy. To think of it, I can't remember the last time I logged in.
Plus if you find you need to edit a message in a thread, there's no need to go to advanced mode to look back on what you are commenting/replying on. you can still view the messages on the thread. Lovr it. Definite bonus that aspect - thank you. Saves typing and putting down thoughts and then thinking, oh, what did so-and-so say, then going back - having forgotten to copy what you had typed to look up their post. Going "AArrrghh" and having to start again. Much much better now.