To add to what's above, yes expect to be based in the PIT system for a while. Several of the beech fo's are probably going the the Dash 8 so the flying for reserves may pick up quite a bit. You may even be able to slide into a hard line within a month or two. If you commute and have a family, reserve will be hell. If you have ATP mins, you'll probably be able to upgrade in around 6 months. Once you're on a hard line, schedules are generally 4 on, 3 off. The plane is a blast to fly, but yes, they are worn out. I feel safe flying them, but they aren't much to look at. They are about 10-15 years old but with 30-40 thousand cycles. Lots of little things will break, but the PT-6 engines are just about bulletproof (and very overpowered for the plane).
It's definitely not the best regional out there, but it's a great place to get in, get your hours, and get out...all while your friends that may go to other regionals are still in the right seat. It all depends on what you want. If you want to take your time at the regionals and possibly make a career at one, then don't come to Air Midwest. If you are trying to build hours and move on, I think it's worth a bit of a sacrifice to get the turbine PIC time more quickly than anywhere else.
If you have any specific questions, post them here or PM me.