Understand the braking system. Choices are magnetic and or centrifugal. IMHO they are much different, I find with my casting style centrifugal works the best. Also buy the best quality that you can afford, you will soon want to upgrade so buying the best could save you money. As far as backlash you must adjust the spool tension and brake to fit your casting style, unlike spinning this is a must. Also you will be spooling with heavier line so keep that in mine. One other differance between the two is playing and landing a fish. With spinning you use the rod, with baitcasting the reel winches them in.
Personally for me I learned to fish with a baitcaster and can not cast a spinning setup with the same accuracy as I can with spinning.