I'd suggest it for testing, but not on a Phone you need to really use. It's a developer beta for a reason- It's great for ensuring your apps are compatible, but if you're downloading/installing just to test it out, expect it to randomly fail.

Specifically - I've seen lots of lockups that need a force-reboot, and apps that don't work or fail in weird ways.

Keep in mind, the POINT of the beta is so App Developers can test it with their apps - That means that nothing is tested yet, and things will break.

Sometimes users will upgrade to a developer-only beta, then write a bad review about an app because it doesn't work right on their developer-beta. These people are jerks.

Overall, I'd suggest a secondary iPod touch or similar, rather than installing on a device you need.

An awful lot of apps I used almost everyday had major bugs with iOS 7 like rdio and some apps would just refuse to open on the beta releases.

It's a risk.