The bad first: there isn't a lot to "do" at this park except see the roses. The fountain is usually dry thanks to the drought. The sidewalks are in poor shape and in desperate need of repair. It's often full of folks going to the Science Center or an event at the Colosseum.
The good: Holy crap the roses. The roses are INCREDIBLE. Thousands of types of roses in thousands of colors - all really well maintained. And there are roses in bloom all year round, thanks to our awesome SoCal weather. It's a beautiful spot in what many think of as a bad part of town. Worth the visit.

When it's in full bloom, the rose-filled grounds are quite lovely. Nice to walk through when you're visiting USC or the nearby museums. Great for photo opps. Near metro stop.