Glycerin is an ok ingredient. If you've recently colored your hair however, you should wait a few days before using a product containing it. Color takes a few days to set, and using glycerin during that period can cause fading. This article should be helpful.

If your hair isn't colored, then the aspect of glycerin to be aware of is that it's a humectant. That means it attracts moisture from whatever is most moist, to whatever is driest. For hair, that means that in dry weather (low dewpoints), glycerin will pull moisture from the hair and into dry air, causing frizz and dryness. In mid-range weather (average dewpoints), that means that glycerin helps maintain a good balance of moisture in the hair, without overdoing it. In warmer weather (high dewpoints), glycerin can pull too much moisture into the hair, causing it to poof and frizz and become overmoisturized.

That's the basic rule of thumb, but there are exceptions. Some people find that their hair plays well with glycerin containing products regardless of dewpoint, others sucessfully use it in high dewpoints (where the "rules" say to avoid it), but can't use it in lower dewpoints.
CG since 11/2011
2c /3a F /Mii, low porosity

Go To Products /Routine:
Clarifying: Suave Essentials Strawberry
Low Poo: Renpure Luxurious Argan Oil
CO: Suave Essentials Strawberry, V05 Kiwi Lime
RO /LI: Tresemme Perfectly (un)Done, Cure Care, V05 Kiwi Lime Squeeze, Suave Essentials Strawberry, Renpure Brazilian Keratin (old formula)
Stylers: LALSG, AIF, HETT, Suave Professionals Firm Control
PT: IAGirl's as needed