Very happy with it.
Pros: You can produce some great pies from it, and get great heat retention and transfer that creates great rise in the crust. Mix it up with a top broiler, and you'll start getting some nice char on your pies. You also get great heat retention in the oven, so if your baking anything, brownies, pizzas, cake, your oven will hold temps better.
Cons: It definitely takes longer for your oven to heat up, since there's a slab of metal that's absorbing heat.
I have the 1/4" and it's fine... if you want higher heat retention, go 3/8 or 1/2. I haven't seen a big drop in the steel temps when I do 5-6 pies, but bigger may help if you're going to do a lot more.
I am, however, considering getting a 2nd one to see if I can do multiple steels on multiple levels to do multiple pies at the same time. It doesn't have a broiler, but the 2nd steel should radiate heat from top and bottom, which may be able to cause char... we'll see.
Short answer: Get it. Well worth it! And you won't ever have broken stones again!