This review is based on two visits to CJ's:
I gave this place two stars exclusively for their support of jazz; I appreciate that they're helping to keep Pittsburgh's legendary jazz scene alive.
Based on first visit to CJ's, I found the food to be average, nothing spectacular, but solid and well priced. The interior was uninteresting but comfortable enough, and the service was average.
The second time I went, however, I found out the hard way that they have a strictly enforced dress code that is pretentious and ridiculous. I wore dark jeans, shirt, sweater, new converses and a leather jacket, but due to my "tennis shoes" the greeter refused to seat me and told me that I (and by default my friend) had to leave. Specifically, I was told that I could wear - for example - sweatpants, but that tennis shoes or sneakers were strictly forbidden. (Perhaps next time I should pair baggy sweatpants with dress shoes; I would certainly be a stylish addition to their clientele!) They also have a sign saying that one must be thirty or older to enter, which is simply absurd (especially since an important part of keeping jazz alive is engaging younger players and fans). Management seriously needs to lighten up; CJ's is not the type of place where such arbitrary rules should be enforced so strictly.
Bottom line: go for the Thursday night jam session, but plan your outfit accordingly.