This Gwenpool Omnibus collects the first 53 comic book appearances of Gwenpool. Because these 53 appearances were spread out over 5 series and a 5 one-shots, you can't really judge them all together with one wide brushstroke, so it's easier to rate them series by series.
As a collection: Great, 5/5 stars. It has all the appearances of the character from 2016 to 2018. Plus it includes the letter pages, little explainers in between a few series, and all of the variant covers of each book in the back. There's nothing really else you could ask it to do.
The Unbelievable Gwenpool: 4/5 stars. It's the 25-issue series that put Gwen on the map. It's written by Chris Hastings, my favorite comic writer (and the whole reason I bought this book), so I am probably biased in this opinion. However, imo this series was pure Hastings doing what Chris does best: taking a goofy, comedic character and writing a long-game plot that has serious moments throughout (contrasting the baseline goofiness) and which endears you to the character by the end of the story so that it is very heartfelt and emotional when the series ends. It's the same formula he used for Dr. McNinja and it's a good formula! I wouldn't say The Unbelievable Gwenpool is among "peak" comic craftsmanship, but it is certainly good and exceeds the "meh" bar that a lot of generic superhero series will set. Speaking of that...
West Coast Avengers: 2.5 or 3/5 stars. Gwen's first proper series after The Unbelievable Gwenpool ended. It's not amazing, this is the typical "meh" superhero content I was referring to. Kelly Thompson writes all of the characters to feel kind of young and hip and quippy, regardless of each of their single allotted personality traits. I get that in team books it's harder to flesh out individual characters and do as much development as you would in a solo title, but even the relationships between characters just feel kind of "eh" and not super compelling to keep reading about. Romantic relationships seem to pop up out of nowhere: America Chavez and Fuse's sister meet each other in one page, and then the very next issue they are dating. Gwenpool and Quentin hate each other and then all of a sudden "haha they're making out now because opposites attract I guess?" Fuse's sister gets obligatory powers just cuz. There's just a lack of depth all around and everyone is too cool and spunky in a bland way.
Gwenpool Strikes Back: 4/5 stars. is Gwen's third series, bringing her back to being a solo protagonist, and it only receives five issues. But it kicks butt! I was pretty skeptical going in after having such a lackluster experience with West Coast Avengers, but Gwenpool Strikes Back reminded me I like reading comics! It's a little bit more of a crazed, dramatic, approach to Gwen than Hastings' original run was, and it verges on tripping over its own intentional plot convolutions at multiple points, but overall I think Leah Williams creates something decently special here. I was finding myself getting emotional alongside Gwen by the end of the miniseries and had trouble putting it down as the finale drew near.
The one-shots are all fine, same with the two ongoing series in which Gwen guest-stars for a few issues each. (Rocket Racoon & Groot and Superior Spider-Man.) They're not incredible, but I didn't find any of them as dull as West Coast Avengers.
Overall, this is a good book to pick up and I'd recommend it to anyone who has read some amount of superhero comics before. There are a lot of in-jokes and meta-commentary about the superhero comic book industry that would go over the heads of people who are brand new to the genre/medium, so for the sake of getting the best experience I'd recommend reading some other superhero book first and then coming to this.