I bought a HW after playing it once on location. Actually it was because my wife, who doesn't doesn't play pinball often, thought it was fun and entertaining.
My initial reaction is that it is designed for the casual player and is more accessible and visually appealing to a more broad population. I haven't spent much time on it to learn the rules, but the shots are solid and fun. A big step up from Houdini and Oktoberfest.
Mustang is a decent Stern title that you don't see that often. I crushed it in a tournament a couple of years ago, so I always play it when I see it. However, it doesn't really stand out to me.
If you wanted car theme comparisons, it should be Mustang, Corvette, Viper. HW is closer to TMNT.