It's better than Hotmail. No obtrusive ads. It's super easy to search past emails, and because of the space given (which is constantly increasing) you can just archive every non-spam you receive.
Additionally, there's a smart spam filter that does a tremendous job.
Compared to an old mail client that runs on my PC, having fast, reliable webmail is really super, I can check my mail from anywhere (and do).
Right now, GMail offers something like 2.2 gigabytes of storage per account. That's a lot of email. I archive every non-spam, and I'm holding steady at around 5% used. And, of course, the available space keeps going up.