I am running it on 10.10(.4?) using vpn, time machine, smb, and I want to say update caching but we only have 3 macs at the office and the rest are PC-heads. It is our main server and seems to be working well. Our mechanical engineer hits the SMB hard but other than that it has an easy life... I also use the box as a git host and itunes server. The only thing I can take issue with is that OSX UPS support is broken.
I haven't had to log into the thing in months, so I'd say it's working pretty well!
If you want to set it and forget it for basic tasks you will like it. If you need to do fancy stuff you should probably look elsewhere. But there isn't really an easy way otherwise to get a VPN server on a mac. It's possible but, kind of beyond my skills without the server app
I mean, for twenty bucks you don't have much to lose just trying it out...