I went there today, after deciding not to trek up to Bridgeport Ct., for the record show sponsored by WPKN, 89.5 on your FM dial...
It is the alternate universe from Mr. Cheapo, another LI purveyor of music. Mr. Cheapo's is probably 90% used product, whereas Record Stop is 90% new. Record Stop is clean, the music they play sounds way better sonically, and overall a much nicer experience. They also grade their used vinyl. I don't know how accurate it is, but it's something.
They have a large selection of LP's; most of what I would look for is there. They definitely don't cater to audiophiles- I didn't see any 12" 45 rpm items that you'd get from Acoustic Sounds, Elusive Disc, etc.
The prices seemed inline with what I see on the internet. In other words, nothing is cheap, but they are not charging any more than elsewhere.
Truthfully, I went on a whim, and did not purchase anything- I was a little overwhelmed. I need to go with a list.