Older homes with smaller kitchens sometimes have the refrigerator inside the "U," but that really eats into the counter space. Most often you'll see a U-shaped kitchen with the refrigerator on the adjacent wall right outside the "U," which is fine. It's still within the work triangle. 
One signature of the U-shaped kitchen is the peninsula. In this case, it doesn't have seating due to the passageway between rooms. The lack of kitchen seating is often the reason people prefer the L-shaped kitchen with an island to the U-shaped kitchen. 
As you can see, the dishwasher is in the peninsula and not next to the sink. That's due to a lack of room, unless you choose to not center the sink. This is one complaint about the U-shaped kitchen. One solution would be to put the sink in the peninsula, but that would leave a long empty counter on the short section of the U. At least here a cook can use the peninsula for prepping and serving.

Here's another view of the previous kitchen. Now you can see the location of the refrigerator: This is where it most often resides in a U-shaped kitchen. Too many times people are tempted to put in both a kitchen table and counter stools at the peninsula. What you end up with is cramped space with too many chairs bumping into each other. If you don't have the room, resist the temptation to do this, it will drive you mad!

In this U-shaped kitchen it appears that the refrigerator and stove are outside the "U," so there might be a few extra steps between the stove and sink. 
Tip: If that's the case, a prep sink by the stove is a great solution — if you're willing to sacrifice a base cabinet. Sometimes in smaller and older homes, you just don't have a choice without moving walls and incurring major construction costs. Make the most of what you have!

A larger U-shaped kitchen with room for an island can be dreamy, but the one downside of this layout is the island doesn't have any seating. 
Tip: It might be possible to fit in two stools at the short end of the island by sacrificing one cabinet or extending the overhang. Keeping the legs, however, will allow you to keep the furniture-style look for your island.