I always apply my gel in the shower. On a good day, I'll conditioner wash, brush in my leave-in using a paddle brush, then rake through the gel. If I have extra time (e.g., on the weekends), I'll apply the gel in sections. But even if I don't, I can generally get decent product distribution and avoid getting my fingers tangled... as long as I brush my hair thoroughly beforehand.
Oh, and I don't have a mirror in the shower. But so far it's worked out just fine.