Its actually quite effective. I use it as needed. I have the generic mix of clindamycin/Benzoyl Peroxide cream, not gel as you have but i believe both are quite effective. The gel might be more harsh on your skin so give it time to adjust somewhat similar to differin cream vs gel. The product it self is not only expensive it does not keep long. I was told to throw it out after 3 months as it loses its potency. When i get mine filled it has to be mixed together on the spot. I am not sure if the gel is the same way. If not then it might have preservatives and such that keep it from degrading over time. Regardless, store away from sunlight and in a cool environment (not refrigerated, just not in like in 80 degrees plus).
I find it my product works better at night because its heavy and takes awhile to absorb and can leave streaks of white if not rubbed in enough. It really effective at drying out the skin if you apply it all over. I did for the beginning of my treatment but now i have sense moved to spot treatment only. I apply after shower/shaving while skin is warm (absorbs better being that im used to it). I drink plenty of water and do not go basking in the sun. I would avoid that to prevent sunburn and increased skin dehydration.
From what i have learned with any BP product is to go sloooow. It takes time to work. It makes you flake, but thats a good thing because its an exfloliant. Just do not over do it.
I also try not to depend on it; when i did use it consistently i would limit my use to 3-4d days a week to prevent over drying sense i do not use moisturizers and such. I haven't used it in over 2 weeks as there hasn't been a need. My skin seems to respond better and quicker when i do not use it consistently. This i believe has to do with the effects of BP on skin healing. Theres a whole science on that..
Anyway hope this helps and good luck.