I've been a tenant in the building on Phillips Ave for three years as a PhD student at CMU, and the experience here has been great. The building is very well-maintained, and though it's the same 1950s brick-building stock as the surrounding streets, the interiors are much more up-to-date than some others I've toured -- in particular, my apartment had new vinyl-hardwood flooring installed right before I moved in, and the kitchen is at least relatively modern with a dishwasher, clean appliances, and updated electrical. No corners cut in the construction or maintenance. That's worth a lot in Squirrel Hill!
Aaron is an excellent landlord and great person and tries his hardest to resolve whatever issues occur as soon as possible. I've had a few urgent maintenance issues and a few less-critical ones, and in all cases Aaron responded immediately and did whatever necessary. He has a team of maintenance folks who do a good job. He makes sure the building stays clean and presentable, and it seems that this attracts tenants who value this, too.
Location is great, of course -- it's right off of Murray Ave, with a bunch of coffee shops, restaurants, and stores, and it's right on the 61C/D bus line to CMU, Pitt, and downtown and the 64 to Shadyside.
All in all, highly recommended!