I use it pretty regularly - mainly post run but have been using it pre run here recently since I've been running in the afternoon.
I just tried the passion fruit for the first time today and liked it. All of the flavors are good and aren't too strong but they are there. As a comparison, the flavor is a bit stronger than Propel but not nearly as strong as regular Gatorade. It's a little on the salty side overall, but that's to be expected.
I don't really know how to define the feeling thing, but I think I notice a difference when I drink it before a hot run relative to when I don't. I definitely believe that it works for me and have been pleased.