Oh, he's great, a great storyteller with a very personal way of telling stories. He's also very good at characterization, with many unforgettable and weird characters. He is long-winded in a Dickens kind of way, but rarely boring (and he is often hilarious). People who don't like Irving generally have a problem with the fact he's basically worked with the same elements for most of his novels. He's explored often the same types of characters over and over again. And there's always amateur wrestlers, and always bears, and New England boarding schools and thus a great deal about teachers and mentors, and always Vienna features one way or another. There's always a sexual awakening story (almost always involving an older woman.. though in one she turns out not to be a woman at all), and weird family relationships, and religious issues etc. Some think it's gotten old, his fans love how he manages each time to tell very different stories, with a different focus, and different themes, but using those same elements (beside a ton of new ones for each novel, however).

If you pick one, just don't go with Last Night in Twisted River. Not that it isn't great (it is one of the best ones, in fact), but to fully enjoy it you need to know his previous books. In that one his main character is a novelist (as is often the case), but Irving played some intricate "meta" game where he gave the boy a skewed version of his own biography (much closer than usual.. but just as twisted in the end) and had him in turn write novels that skew his "real" life experiences and end up being variants of Irving's own novels (but somewhat mixed up and re-arranged). So you end up with fictitious origins and sources of inspiration behind Irving's novels.(Irving is very enamoured of the idea that a main function of a novelist is to lie.) In the background is woven his vision of the American experience from post WWII to 9/11, which is a kind of "fuite en avant".

His most atypical (and weirdest) one is A Son of the Circus, which is set in India mostly. An imagined India, as Irving has never set foot there on purpose (as his character as a very personal vision of it). I loved that one.

The World According to Garp is his most successful and has gained a "classic" status, but personally I think he's written stronger if somewhat less popular ones after that. If Garp has its reputation, it's mostly because it was the first popular one, and the "surprise" of Irving's weird brand of realism had less impact the second time around and afterward.

Among my favorites would be Until I find You, the "unreliable narrator" story (a minor feature in other novels, the central element in this one), narrated by a 4 to 9 y.o. and later adult whose single mother, a tattoo artist, travels through Europe running after the boy's dad who abandoned them. The second half of the novel, after the boy has become a famous Hollywood actor, unravels all the first half. Then there's Cider House Rules, which is brilliant. And I also love A Prayer for Owen Meany. Hotel New Hampshire is another very good one. Also "A Widow for One Year".

His new one, In One Person, which brings to the front a secondary theme in almost all his other novels (sexual/gender identity) is also quite good. The more he gets old, the more literature itself and his vision/philosophy of what is a novelist and what writing is to him is a major theme of his stories.

Basically with Irving, you can go with the story blurbs and decide which sounds most interesting.

The only one that I haven't yet read is the Fourth Hand, which has got very mixed reviews.