For me, John Irving is a bit of a guilty pleasure. There's a lot of things wrong with his books, many of them being mentioned by a previous reviewer. He doesn't always give his characters a rounded personality (particularly in the case of the narrator, probably something borrowed from The Great Gatsby, a book mentioned a lot in Hotel New Hampshire) and some of the events are a little too bizarre and unlikely to be believable.
Despite this, I've enjoyed all the John Irving books I've read (this one, Garp and Owen Meany) the stories are ones I can get lost in and they're the sort of books I'll sit down to read for half an hour and still be reading two hours later without even realising.
If you pick at the Hotel New Hampshire, it falls apart, but it's a great read.