Seems shorter than Cold, Cold Heart, and about as long as Harley Quinn's Revenge. Maybe a bit shorter. Definitely not as short as the Harley Quinn and Red Hood Story DLCs. Seems like it's reminiscent of the Panessa Studios sequence from the main game, since you have Robin around to switch to occasionally. Babs can use her hacking device to mess with machinery around thugs. (For example, she can remotely activate a panel to electrocute a thug, or activate one of Joker's traps to unleash Joker's gas on unwitting thugs). Concludes with a dual play boss fight against both Joker and Harley Quinn. Looks like it's pretty similar to the Nightwing and Black Mask boss fights from the Harley Quinn/Red Hood DLC, since there's a ton of thugs to distract you as well. There's a bit more flashiness on display though, since there's a QTE that can be activated that's a bit similar to the Deathstroke fight from Origins.
Beating the above puts you at 100% for DLC completion, so after beating it, there's not much to do but go for the PSN trophies/XBL achievements. (After beating it, you're free to roam the park, apparently, so that was probably the intention) There doesn't appear to be any additional skins available for her, either.