Today, Park Cafe sits in the middle of Munich's business district, and the large beer garden behind the cafe draws a decidedly business crowd. Stopping by after work, many people will still be in their business attire, enjoying a German-style happy hour with their colleagues. Park Cafe thus has a bit more of an upscale feel than some of the other beer gardens in Munich, which by my definition at least, are the "congresses of the plebs".
The best thing about the Park Cafe Biergarten is the pleasant and convenient location in the middle of the city right on the edge of the park, and it's size. It's one of the larger beer gardens in central Munich, and is a good place to arrange large group meet-ups, including birthday parties. If the weather isn't cooperating, it's also easy to move the party into the spacious cafe restaurant. Other than that though, I would so that the food and drinks aren't anything special, so don't go there expecting to be blown away by a superior dining experience.
Also, Park Cafe is a party destination on weekends- they often sponsor large themed-parties, and have live music and DJ's. It has a well-known after-party during Oktoberfest, but I've actually never been to any of those parties, so I can't offer any specific commentary.