I started using Feedburner because of the email subscription option. I still have it activated on some sites, but I've been moving my email subscriptions to the use of a Gravity Form which integrates with my MailChimp account where I have RSS subscriptions activated.

Not as simple of a solution to setup, but allows me better analysis of subscriber activity and much nicer looking emails to them.

Down side is no Adsense in these emails currently.