it has a decent spam filter, a "mute" function to mute spammers,
and 5 auto-configurable (+ more manually configurable) inbox tabs:
- primary - conversations and important stuff
- social - facebook and other junk
- promotions - ebay, companies you subscribed to, etc
- updates - releases, info from companies, etc
- forums - emails regarding forums
then you can also star the mail with different "stars" and organize it even more yourself, but i never used that, so i can't explain it accurately.
the spam folder is located in the "more" option of the sidebar, and it auto-deletes 30 day old messages, but i believe that is configurable too.
my move was pretty painless, because i never actually changed my addess, just started using the new one for new accounts.