This is an insanely awesome way to work with your e-mail! Google have essentially turned your e-mail inbox into a massive todo list, which as it turns out, is actually a nice way to treat it.
The bundling is great, and is pretty accurate from what I’ve seen. Also, the extra meta-info they add in to some e-mails seems to be quite useful - things like flight details, or purchases.
Reminders is also great, especially for people like me who e-mail themselves things to remember.
I’m a big fan and really wish I could use it with my red-taped security controlled corporate Exchange e-mail account too.