It's likely past the point for anyone looking for rents, but I lived with Walnut Capital for my masters and had zero complaints.
One thing you must understand about Pittsburgh is that it has a very dodgy management culture. No matter where you stay, you will likely deal with the management company showing your space the moment you give notice, they will always hike your rate when you re-sign, and they will be reluctant to tackle any minor complaint.
That said, my best advice is to search the units very carefully and make your decision in that regard. I had nearly no interaction with my management company while staying at Walnut Towers, but because the unit was in very good shape and the pseudo-landlord was helpful (albeit unpaid and overworked) I didn't need to interact with them.
Squirrel Hill tops Shadyside for affordability, proximity to shopping, quality of restaurants, and ease of access to the parkway and buses.
Crime is everywhere, even Shadyside and Regent Square. It is not uncommon for apartments on the groundfloor in plain view of the street to be burglarized. Always get a place on the second+ floors.
Snow will be a problem without ample parking. Pittsburgh has one rule: respect the chair - if there aren't enough parking spots in a lot, expect to find lots of cleared areas with folding chairs staking a claim. It's very nice if your unit has ample space.
When you move there, go to Silk Elephant on Murray and get their curry. You'll thank me later.