I'm primarily a mathematician, and some of the the ODE systems they use (and the professors working with them) are right up my alley. Carnegie Mellon is also well-known as computationally strong... if you've never seen their Robotics school in action, you'll have to, they build the coolest things. The location helps me, too - I'm from Youngstown, Ohio and I've been to several conferences in Pittsburgh, and they've been to at least one of ours, so I've seen the quality of their students first-hand. One of my advisors for one of my research programs had his Ph.D. from Pitt in mathematics dealing with neuroscience. I feel like I'll fit right into their family. I also really appreciate that CMU and Pitt are working together, I think it gives us a much broader range of options and resources. I didn't have a particular biological project in mind when I applied or interviewed, so I don't know how to help on that end, but there seem to be a lot of options there, too. I'm interested in the systems modeling of inflammation related to influenza, and they may be starting a new project looking at modeling malaria within the mosquito (instead of just the human element). The standard SIR model is getting a little overdone, so I appreciate that they're coming at these issues in a new way.
Pittsburgh is a nice city, too, although most cities are nice once you get used to them. It is somewhat disappointing that you ALWAYS seem to be walking uphill in Pittsburgh, but... it'll tone your calves? It's a newer program, and they haven't had a lot of recent graduates, so they can't offer you the "All of our graduates have tenured faculty positions!" speech that more established programs might be able to offer, but I have no doubts that they will succeed. I think Pitt (or CMU?) is trying to start up an undergraduate Comp Bio program, which doesn't necessarily help us now, but that means they'll have one of the first undergrad degrees, a master's degree, and a Ph.D. degree. Obviously they have the funding and resources for growth.
As far as recreation, Pittsburgh has a zoo and several sports teams and theatres. There's also Kennywood, if you like amusement parks, or... for a 3 hour drive... Cedar Point in Sandusky, Ohio. Cedar Point is pretty much the best amusement park EVER. They're also fairly close to Ohiopyle if you like whitewater rafting or the outdoors in general. The summers are generally pretty warm and gentle, although there is a significant amount of snow and cold for 4-ish months in the winter. Cost of living is lower, so you can get a nice apartment, or even a house if you go a little further out of the city and don't mind commuting in.
Ummm.... yeah, that's about all the knowledge I have on Pittsburgh, lol, although I'd be happy to answer any other questions. It's really not that far from where I already live.