The one thing I will say is to be sure what you are booking. There are several terms that are loosely tossed about here....limo is one of them. Are you booking a true limo or a Lincoln Towncar? Most companies use towncars. Limos are usually of the stretch variety.
Based on the cost of $160, you are most likely getting a true limo..towncars usually cost in the area of $100-120 r/t, plus tip.
I haven't heard anything about them either way though.