Driving by for many years, I was once ahead of schedule and stopped in to check it out. There was nothing there other than a chance to stretch your legs before entering the city. Not sure why tripadvisor has it as being at the end of Jasper Avenue as that is not the park all the reviewers are talking about...
We tried to stop in to use the restrooms, but they were closed. It was a Thursday afternoon, so not sure what was up with that. Would try again the next time we go that way. Looked like a well maintained area.
The staff here is terrific and they'll outfit you with all the information, maps and literature you'll need before heading south into the park -- and you can purchase your park pass here. This immediate area is also your last chance to do serious shopping and outfitting before heading south so stock up here on your essentials.