In general it sounds like a great deal -- freelance-type hours but with a regular paycheck and health benefits.

I had a similar position once and it was great for my family. I never had to miss anything important and had no commute. The only con was lack of face-time with peers.

What are your concerns? It sounds like you are looking for some hidden gotcha.

EDIT: I posted my comment prior to your edit. So, here's my counter-edit :-)

I suggest talking to an accountant. He/She will be able to tell you what costs to keep track of and how to put aside enough for taxes -- and possibly if you're getting a good deal.