We have a new puppy. We got one of those wire pens for him. Unfortunately, he almost immediately figured out he could climb the cross wires! He was out in a flash. SO we got this pen. It is almost perfect. It will be perfect when we get done. The bars are in general about two inches wide. Those he cannot get through. But the gate is a different matter. The bars around the hinge and latch areas are about a half inch wider--probably to accommodate the mechanics of the gate latch and hinge. But that is just enough wider that our puppy can get his shoulders through. Maybe the rest of his body, but we intervened.
Roll with it. Some manufacturers claim that their play yards fold compactly and easily, which is especially important if you'll be traveling with it or assembling and disassembling it often. See for yourself how easy it is by practicing on floor models in the store before you buy. Some parents find that while they can collapse their play yard in a jiffy, fitting the whole thing into its travel bag is almost impossible. If traveling with the play yard is important to you, look at the travel bags when you are shopping.
Some basic models may be easier to cart around because they don't have any extra parts. You can also look for bags that leave the play yard's wheels free, so the whole thing can be rolled once it's packed up. If you plan on taking frequent trips (especially by air), you might want to consider a heavy-duty bag that you can buy separately, such as the Rover Gear Easton Travel Yard Bag (about $34).
Perfect for a variety of different uses. Having 3 kids under 5, I've used my fair share of baby gates and play yards. The Evenflo play space is very portable, lightweight and easy to fold down and take on the go. You can add and remove sections with a simple push of a button. I'm currently using this gate to block off my fireplace from my one year old who's fascinated with climbing on it. Also, I will be using it during the holidays to wrap around and block my kids from getting into the Christmas tree. I would recommend this gate.