I feel like the pros and cons are different for everybody and will depend on what's important to you. For myself, I was looking for a school that didn't require group work, was affordable, and I could do at my own pace. WGU fit all those so they are my pros. Cons? Graduating with is a 3.0 is a con for me, but it doesn't bother others. I was also concerned that since it's competency based, I wasn't going to learn anything new but that hasn't been the case.
After being in the program for just 2 months, I have to say I'm thrilled with WGU and I'm glad I chose it. My mentor is fantastic, I'm learning things, and I wish I hadn't spent so much time making up my mind about WGU! (my stumbling block was the 3.0 GPA)
I tell everyone I know about WGU because I'm so happy with it.