The Fault in Our Stars aside, John Green is a one-trick pony when it comes to characters and plot. 
 But man, do I like his pony. 
 Yes, Q and Margo are pretty much swappable with Green's other protagonists and their love interests, and the "sidekick" characters are practically the same with just different quirks--but this isn't necessarily a bad thing. Looking for Alaska, An Abundance of Katherines, and Paper Towns felt like a series with similar characters exploring and coming to grips with death, religion, and identity. 
 Paper Towns is certainly the most polished of the three, with Green going off on fewer tangents and only repeating himself when appropriate. Using Whitman as a framework worked better than I had expected it to, and the tone is perfect for young adult. The characters (although recycled) are still fun and fleshed out; my only complaint is (view spoiler)[that Margo (probably the most interesting) is so absent throughout the novel, and for a novel about identity and finding out who someone really is, it doesn't allow us much room at the end to do so. I think the ending is John Green's best and he handles it beautifully, though, and I'm sure Green would say that the point is the reader only "knows" Margo through the mirrors of the other characters, but it feels like a lost opportunity with a really great character. (hide spoiler)] 
 This is a top-notch YA book that's a fun, quick read for older readers as well. If you aren't a fan of John Green then this certainly isn't a must-read (especially if you've given TFiOS and Looking for Alaska a shot), but if you like him, expect more of the same and enjoy.