Flew for them 2005-2006. I was based in MYR on a DHL route so I didn't really work that hard. DHL had their own loaders.
The good... Great place to start out if your below 135 PIC mins. No autopilot or GPS so your really flying and polishing up your skills. Training was a lot of fun. I'm not sure if the farm house is still being used in MKE but some people say its haunted. Upgrade was consistently about a year. The Shorts is a fun and easy plane to fly. I miss flying the Irish Concorde. Shorts can handle ice like a champ. Check out
this video.
The bad... If you fly a UPS route, you will be loading the freight. Beckley, WV route was 6,000 pounds every night. Also UPS route means spending nights, Thanksgiving, Christmas in Louisville. Time off was very difficult to get. My friend was told he would have to work on his wedding day. And yeah, the FO's seat is almost always a moldy heap of stink. If its raining, the escape hatch drips all over you.
Keep in mind my experience there was with their old chief pilot who was a bit off in his own way.
I'm not 100% sure but the on demand side of the company was dead a few years ago. If that's still going, its 100 times more fun than the scheduled stuff but the flying is inconsistent. Rarely would those guys top 30 hours a month.