Make a note that this is a zero issue. It goes a little off the rails (in a good way) and is not necessarily fully indicative of what we can expect in the series. The first thing you'll notice is Harley breaking the Fourth Wall and even having conversations with Jimmy and Amanda. It absolutely works in the story and adds an incredible amount of humor. But concerned fans needn't worry that this is how the series will play out (it's only in this zero issue).
As is evident on the cover, there are a lot of artists on this issue. The reason Harley breaks the Fourth Wall is over the idea of a comic being made of her. This is where we get to see a sort of interview process with the art. What it really means is we are treated to page after page of incredible interpretations of Harley and her wacky sense of adventure and violence.
The art alone would be reason to pick this issue up but Jimmy and Amanda's dialogue is the icing on the cake. While reading this, you can simply sink into your chair and get comfortable while you enjoy the story. DC Comics (especially in the New 52) tend to stay pretty serious. With Harley's nonsensical tone, you simply have fun reading this comic. Some of the pages the different artists provide are so incredibly insane, you really do feel like they've tapped into Harley's fractured mind. The next issue will delve into more serious business (or as serious as it can be for a Harley solo series) and this is the perfect warm up to welcome Harley back.
As long as you know what you're in for with this issue, there isn't anything to complain about. It's a fun showcase of who Harley is and what Jimmy and Amanda have planned with her. Having a bunch of artists gives it a party feel.
Harley is back in her own series and Jimmy Palmiotti and Amanda Conner are setting the stage for her return. We've seen Harley go through a bit of a transformation in the New 52 and this issue shows they understand who she is at her core. As a zero issue, the series blasts off into a crazy and wacky beginning with a party atmosphere with all the artists contributed their takes on her. This issue will make you laugh and it will make it clear you'll never know what to expect in the series. Perfect for a character like Harley.