Full disclosure: I've known the owner for about five or so years, meeting him when he was the bread route jobber supplying DiNic's at the Reading Terminal with bread, first from Carangi's and later from Sarcone's. So I'll try to stick as much as possible to facts rather than opinion.
The owner, Danny, is clearly a bread guy. Most important fact: it's a sour dough crust, with a very mild tang, And the starter for the sour dough doesn't come from a package. Danny just set out some dough to let the local yeast in the Haddonfield atmosphere do what it does.
Unless you tell him otherwise, your pizza will be baked to well done, with good char on the bottom but retaining good chew. The only time to order pizza less than well done is when you plan to finish the cooking process back home. (For that I put a baking stone on my backyard Weber gas grill the crank it up: temperatures get up to 600F.)
Angelo's uses quality ingredients, and though I haven't tried it yet, I'm told by a more frequent customer he's now even making his own mozzarella. Now, if only Danny offered anchovies! I have to bring my own.
As i warned in the beginning, Danny is an acquaintance so I'm sure I have some bias, but I hope these facts lead you to try the pizza at Angelo's. You'll be hard-pressed to find a better pizza east of the Delaware and south of the Raritan.
Whenever I'm back in my native North Jersey I had for here, since the one bakery like it I knew in Philly closed a few years ago. The Seven Layer Cake is a blast from the past, as are the sugar buns and just about everything else. And I second the endorsement of the salt sticks.
Obviously, one earlier reviewer had a bad experience at XYZ before having an opportunity to taste the food. That's too bad: XYZ has been around so long because of the food's quality and the pleasant, efficient service.
I've never had the rude experience a couple of the other reviewers write of. Certainly, I've never seen such behavior by the owners. It's possible, of course, that an employee was so rude, and that reflects poorly on management for its training failure. (Fair warning disclosure: I've been going to XYZ for so long that the owners know me and have become casual acquaintances, even though I live five states away.)
Getting a table at any superior restaurant on Mt. Desert Island in peak season does usually require a reservaiton. XYZ is no exception. You might see empty seats if you stop by when they first open, but if they say they can't accommodate you, that's because they have reservations to fill them. And during peak season, most folks dine later, beginning at 7 or 7:30 p.m. or so, to take advantage of being outdoors. So If you show up at 6:45 and it seems empty, odds are it will fill up in half an hour. So if a restaurant is fully booked beginning at 7:15, they aren't going to seat a walk-in at 6:45.
Should you visit XYZ (and you should, you should), try whatever on the menu appeals to you. But if you feel adventurous, and it's available, try one of the tongue (lengua) dishes, which they usually serve as a main course as braised slices, though sometimes it's an appetizer, served cold and with a paté-like texture and taste. Should fresh blueberry sorbet be available, go for it. Oh, they also make killer margaritas from fresh limes. Have a designated driver.