As a Protools dongle or as an interface? I don't like any of the MBox family as an interface. If you need a PT dongle then there is the Micro.

I have one. It's ok. Stable on my system. ProTools LE 8 is very nice. I love to bash ProTools. It's a love hate thing. I'm not particularly fond of their hardware but ProTools has a lot of users.

The Mbox2 mini is every bit as cheap an interface as you can imagine it would be. If you can afford it go get the Mbox 2 instead. It's surprising how much better the box is for an extra $150.

That all being said, wait a little while. Avid will be releasing some news in the next little while. Probably within the next three weeks. Wait for that news as it will likely mean a free update/upgrade. I can't mention what as I really don't know. I have my suspicions but that is only speculation.

There are many other interfaces out there. All with their own little problems.