Marv's place was excellent! I stayed there for a month while I had a fellowship at the Newberry Library, which was within walking distance. The Red Line subway is right on the corner, which was very convenient--about 10-15 minutes to the Loop. The neighborhood is full of excellent restaurants, bars, and shops, and walking distance to now fewer than 4 grocery stores.
Marv was a great host, he was waiting when I arrived and even had snacks for me. He even brought an additional lamp so I could study. Really considerate and accommodating.
The one thing I will note is that the bedroom window faces onto a busy street and therefore can be noisy. I'm a sound sleeper so it didn't really bother me, but if you're a light sleeper you might want earplugs. But if you want peace, you wouldn't be interested in such a vibrant neighborhood, right?
I would highly recommend this place, and I'm definitely interested in staying here again the next time I'm in Chicago.