Overall I thought it was good, because it was fairly realistic, at least as far as the storyline. No tornadoes, nothing really that spectacular over the entire trip, and lots of driving. I know it's not the exciting, seat-of-your-pants type of show that's been wildly-popular the past few years, but the realism made up for the lack of excitement IMO.
As usual, the editing and narration were low points. It's bad enough anyway, but when you have a voice-over that's trying to add drama where there simply isn't any, it's 10 times worse. Then again, I had to keep reminding myself the show was about the driving conditions, not about storm chasing.
Jim is obviously more comfortable in the role of TV drama, as his dialogue (IMO) co-existed naturally with the overall narration's attempt to build intensity (where there really was none). I thought Simon came off as more genuine, just a guy who goes out with not much and often gets a whole lot. His low-key demeanor and approach was interesting to watch.
So yeah, I thought it was a decent program, but my bias due to experience refuses to allow me to be objective regarding how shows are put together. I could do without the fabrication, especially in a show where 90% of the time there is nothing happening. But...that "dullness" is what makes the show about as close to real as it can get in Hollywood, and for my money, that's a win.