Good is all relative. If you have stellar grades, then the fact that your 1L summer job is your only work experience wont' matter as much. If you have decent grades (ranked 30-40 % maybe), but law school is a second career and you have incredible work experience to bring to the table, then you're still in the running for good jobs. I'm sure even lower grades aren't the end of the world, either; at that point, more and more is based on your personality and networking skills, as well as how committed you are to sending out targeted resumes, pounding the pavement, etc.
For OCI/job fair jobs, you're likely going to have to be top 10%. But tons and tons of firms in NYC don't interview on campus. It's more work, but doable.