Some thoughts on the new units:
Ive been playing a game as the Persians with 2.4. Seeing my starting position amonsgt the hills and mountains wasnt too good I opted for an offensive strategy making sure I built the Statue of Zeus wonder. The new Elephant archer unit greatly complimented this wonder. Needing elephants anyway, I had 2 or 3 of my cities building the new unit, and was able to conquer the various Middle eastern and Indian civs.
I didnt realy built any Camel Riders, although they do add alot of flavor to the game. What doesnt add flavor is now that Im in the 1970s with Tanks, Mech infrantry and stuff Im still able to build Camel Riders and Elephant Archers (as well as Hussars and Cavalry btw). Maybe those units could be made obsolete around Militairy tradition, or at least Motorised Transport.
Furthermore, I was thinking it might be an idea to add a new Camel unit later on (seeing you just need it for the early Camel Riders) - something on the lines of a Lawrence of Arabia desert guerilla type unit perhaps?
Just some thoughts.