Only bad thing I've heard about Matamps is that they're quite delicate and don't like quite the same lugging around that people are used with other amps (marshalls/Oranges).
I've always wanted a matamp though. Awesome things.
They're a bit oversensitive about blowing fuses, which I suppose is better than blowing a power transformer. Mine has only had one problem apart from a popped fuse and a dodgy valve, and they fixed it for me on the spot while I played through their speaker wall upstairs.