If you are using a decent amount of weight it forces you to use as technically correct form as possible.. by that I mean you stay upright as you descend far more than a back squat... I find that you feel that you are going "deeper" into the front squat moreso than the back squat as well. Fries your abs as they assist you in keeping the weight over your delts and clavicles.
Also great as a assisting / transition exercise to overhead squats
Just search the site for that pic of Dave Draper front squatting 315 from back in the day. Inspired yet ?