A couple of great things to check out are the bulk spices. You can really get some wonderful deals hear, and you are not paying a lot for the packaging. I love that the spices are housed in an antique card catalog.
The other thing that is special is the cheese counter. You can get some really excellent local artisan cheeses at Marty's.
I think where Marty's excels is in their Cafe. Really excellent food at very reasonable prices. They have a creative menu and food you can rave about.
There are also lots of special events and classes at Marty's, make sure you get on their mailing list of check their calendar.