I'm not overly concerned with the glycerin, since from what I have read about it, it doesn't cause an insulin spike.
Thus, as long as the protein in the bar makes up 40% or more of the calories - I'm good to go. Of course, I try to get the lowest carb, lowests fat/sat-fat bars out there, but personally I have found that the Pure Protein bars taste great - especially the Smores flavor - its outstanding!!! (30g protein, 5 g carbs, 4.5 fat, w/3.5 of that being sat-fat).
I generally eat two bars a day (get them on GNC day, a box of 12 for $20, works out to $1.67/bar), and use them for a small meal (10 am and 4 pm).
ER