This is the sequel to Mel's first book, From Here To Maternity, and they are similar enough that it's fair to say that if you enjoyed the first one, you'll enjoy the second one just as much. That said, there are some key differences.
The first thing that is obvious is that the experience of doing the first book has left her a better writer. The structure is far better in this sequel, and I found the laugh out loud moments were built up better than in FHTM. Mel's writing style is natural, personable and flows well. The only negative point is that the ending is a bit flat and seemed to come out of nowhere, although I suppose that's only natural given that the subject matter in the first book led to an obvious finale.
The second point is that this book is darker than the original - I guess whether that is a good or a bad thing depends on your tastes, but I found that some of it (especially the frequent drug references and the fairly bleak final few chapters) made the book less likable than FHTM overall. Whether the darker tone was intentional or not I don't know, but if there is a third book to come (and I hope there is!), I'd prefer more of the cheeky sense of fun that the first book had to make a return.
Other than that, the rest is what you'd expect - good gags, an eye for absurdity and characters, and a lot of smart one-liners. Highly recommended (even if I do think FHTM is just a tiny bit more likeable).