Let me preface this by saying that this review is being graded on the dive bar scale, not the same scale as you would rate a fancier pub.
Grossman's is a locals watering hole, normally nothing very exciting, until the music starts. The place is a great live blues and jazz bar. The acoustics are awesome and the music is brilliant! However it has some flaws. First flaw is the lighting in the bar area, wow it's bright. Picture the lights you would have in your kitchen. On the side where the stage is the lighting is OK, but the bar area is too bright when you want to have a pint. Flaw number 2 is the price of beer. It's not overly pricey but for a dive bar you normally don't have prices similar to the "faux irish" pubs that have blighted the drinking landscape. Flaw 3 is the paint job on the walls. I know this is a tad nitpicky but the walls look like they were painted in the 60's, inspired by a hospital. On the plus side the washrooms are clean, obviously recently renovated (my friend said that the last time he was there they were awful) so that's a good bonus.
My overall opinion is that you should go to grossmans if you love blues and jazz (and it's brilliant for that), otherwise I see no logical reason to go there.