No, I will not be giving out invites...
Been playing around with Gmail. You can't just subscribe, someone has to invite you to get an account. Often you see forums with someone offering or begging for a Gmail account. Don't bother asking me, I gave away most to friends and family and gave one to a random guy on a forum.
Accounts are very in demand since the people at Google are the ones who created Gmail. They offer a gig of free space. This was the main reason that most free email accounts increased their account size limits from something like 6MB to hundreds. All hail Adam Smith and his invisible hand. You can read more about Gmail's features at Gmail.google.com.
Every time you invite and the guy accepts, it puts him/her in your contact list automatically, which is nice and convenient for friends and family, not so much to any random people you invited (waves 'hi' to random guy I gave a Gmail account to).
There are small text ads to the side but they are unobtrusive. Let's hope they stay that way. There are lots of settings and stuff.
Keyboard shortcuts:
You can hit "j" and "k" and move the focus to the email you want. Hitting "y" makes it deleted/archived. To compose I can just hit "c".
There are a huge number of shortcut keys.
Filters:
There doesn't appear to be a limit on the number of filters you can apply. Most free email accounts limit you to about 10 or 12. I have any emails cc'ed to "russellnz" and "russelllz" sent to trash since those are mass computer generated spam emails. I'll add my usual viagra/penis/xxx/flea-bitten-manginas/etc. filters in if too much spam gets in.
Show snippets:
Shows the first few words of an email, like in Google searches that show the first few words.
Inbox:
You can "star" the most important email exchanges.
By exchanges I mean the email conversation you have with someone. They are grouped together like index cards, so you can keep track of past messages quickly. Echoing Google's pared down design style, everything is very uncluttered, with the normal From, To, Date, Subject, and fields hidden. You can click and have them appear instantly.
Replying is very quick, I hit reply and the screen stays the same except that the bottom has a reply form field appear (again, instantly).