Yes, a bit late in the game, but I refused to pay $$ for something that was given free to people. usagichan from Arstechnica was kind enough to send me an invite.
First, I contemplated for a few hours for the username. The minimum length is 6!! which is way too long for my first name. or even my first name + last name initial. And since my last name is so complicated, I really didn't want to put it in there. Reluctantly, I added my middle initial in it too. Kinda sucks because I never use this account name before.
The interface is very clean, like any other google interface. I like the keyboard shortcut so you can move around the menu without a mouse (and the up/down arrow is j/k, same like in vi). i'm still trying to get used to the conversation list - hard for me to figure out who wrote the last email within the conversation.
hm.. i'll write about this some more later.