I think the idea of renting an airplane away from home is moderately appealing and I've done it 3 times (none via OpenAirplane), but each time with a local instructor, because I wasn't going to use an away-from-base rental airplane for purposeful travel.

The desire to rent an airplane without an instructor (what OA enabled) isn't that much higher for me than renting one with an instructor. In Iceland, I wanted to fly around and look at the terrain and nature. I flew the airplane, but have the instructor knowing where we were, all the radio procedures, and having a "walk up, get in, fly, go pay, walk away" experience was worth the modest instructor fee. Same with the two rentals I did in Florida; in those cases, I was trying out new aircraft as a potential type to purchase and had no reason not to have an experienced instructor on board (in fact, it was a big plus).

Now, the fact that I didn't do what OA is best at means that maybe I don't really see the advantage. If we're going somewhere within about 700 miles, we probably have our airplane with us. If we're going farther than that, we're probably not going to then want to rent an airplane to sight-see and need to not have an instructor on board. If we go to Hawaii, we'll surely rent an airplane and instructor.

I feel bad for the obviously passionate founders who had their company fail to thrive.