I've only been through Pazin on a one-day tour. It's my impression that it's the administrative center for Croatian Istria. I am sure you can find decent restaurants, and of course there are grocery stores. Aside from a zip line and I think a small historical museum, I believe it's not long on major tourist sights. (I confess to not having checked on Trip Advisor, something you definitely should do.) Pazin does have a good central location. Not having driven in Istria, I am not in a position to comment on any challenges basing in Pazin might present.
I would warn you to stay far, far away from the toilets in the Pazin bus station. They were the filthiest I have ever seen, and I've had a lot of opportunities to compare.