it requires an invite right now because it's still in beta.
as far as advantages vs. disadvantages... it depends on whom you ask. I'm not saying i agree or disagree with any of this...
1) given that much storage, you never need to delete an email 2) you can use googles search technology to search all your emails 3) ads will be inserted into your email that target your likes/dislikes 4) i assume they back it up, so you will never LOSE an email 5) it's free 6) you can access it from just about anywhere, quite easily.
There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors
Can you send me 2 invitations? Don't want to seem greedy but I need one for myslef, and with a few sites I am running one for webmaster issues. Can you send me a Private Message, or do I have to post email addresses? Don't want to publish emails, spam bots have been pretty nasty lately.