Our bus from NYC to BOS was very uncomfortable for two main reasons. The first one being no air condition or ventilation for the entirety of the trip. The bus driver commented on how this happens from time to time. The second reason was compounded by the first since the bus smelled like a porta potty. I sat near the front of the bus and could not imagine how bad it must have been near the back.
Take Megabus instead. Several months ago I did the same trip and paid $12 compared to Greyhounds $50 and experienced no issues.