I interviewed there about two years ago. I got to the final round, didn't get an offer, but eventurally found an offer at another larger firm. The pay for the clerking job is so-so (35 I think, I can't remember exactly), but that shouldn't deter you if you're looking for a start in the business. Many of the guys that trade at Lerner seem to be very good and probably make a lot of money.
His group is small but well known on the floor. I think there are about a dozen guys now (I heard a few guys have been there for 10+ years, which is forever in this business, but I can't confirm that), plus a whole bunch of guys that trained there, traded for a while and went on to other firms.
The main guy, David, if you interview with him, can be really difficult. He quizzes you, tries to break your concentration, etc. Now that I trade myself, I realize exactly what he was doing and why.
The company is totally legit, the main guy is supposed to be a real ball buster, but that's the business.
Good luck in your interview, you'll need it.