From what I've heard Horizon is a great airline. My uncle works there and loves it. You can check the pay section of this site to see the pay. They're one of the best paying regionals and I think they offer the highest first year pay.
QOL is great. He has told me that the company really cares about their employees. He had a buddy who left Horizon for Alaska and ended up coming back. The cheif pilot gave him his old seniority number nad everything.
You can find the route map on their website. They fly all over the west coast and in the mountains. They've taken some routes for Frontier. If you want to fly a jet or get a quick upgrade it probably isn't the airline for you. They've converted the majority of their CRJ orders to dash 8s. A lot of people who go there are making a career move, they're there for the long haul.
Overall I've gotten a great impresion about it.