Arabs tend to make fantastic lower level eventers due to their stamina and willingness. However, the biggest problem people encounter is the jumping ability of an Arab. The grey posted here is a perfect example of the less desirable typical jump of most Arabs - head up, knees not tight and hanging a bit. They tend to jump hollow and can be difficult to teach to round over a jump so it's usually best to just find a sportier Arab better suited to athletic movements.
Crabbet Arabs are renowned jumpers, and super sporty. My grandpa sold one of our purebred Arabs growing up and he was competing and winning in 4'0" jumpers, and a low level eventer well into his 20's. He was only about 15hh, but he used himself so well, he just had natural springs in his hocks.
My own Arab mare has a very sporty and correct jump, and I curse that she hit 14.3hh because she would have made an adorable pony jumper.