i must admit that the Brilliant's AF Assist Light isn't spot on but mount a telezoom on it and it's approx at the centre of the frame.
I've been using cheap 3rd party flashes and yes, the Brilliant flash lacks in build quality. even the cheaper Yong Nuo YN460 Mark II feels much solid beside it. However, the Brilliant flash has got every function that you'll need, even the 2nd curtain flash which, not all 3rd party flashes supports.
At the price that i got it at, no major complains from me. You might want to try the Sunpak ->
http://bit.ly/cCxmZO
Oh yes, the Brilliant flashed worked on the 30D/40D/50D and 5D MkII. Haven't tried any other models but since it can work with the 5D MkII, should be safe.