I began using Differin to help clear up the worst breakout I have had in my life. Last year I used a TON of different skincare and makeup products without patch testing over several months, and I really messed up skin on a deep level (disrupted my acid mantle I guess). My clear, normal skin turned into parched, red, flaky mess with cystic acne. I also developed whiteheads (milia) everywhere except my forehead. Trying to clear my acne with AHA, BHA, oil cleansing, chemical peels, etc. only made matters worse. I finally simplified my routine to one basic cleanser, moisturizer, and benzoyl peroxide for spots, and I stuck with it so my poor face could return to (mostly) normal as far as hydration/pH is concerned. My cysts calmed down a lot, but my face still looked rough with all the milia and blackheads.
I chose Differin since it was supposed to be the most gentle of the retinoids, even though all the reviews warned that it would take a lot longer to clear acne than RetinA, etc. After using Differin for about 8 months now, I can say that this is entirely true. I started slowly, using a small amount every other night for a few weeks, and I gradually used it every night without any irritation. I also found that I could tolerate more than a pea sized amount for my whole face. Initially I did have some heavier purging in my problem areas--milia coming to the surface made big pimples 2-3X weekly. This lasted a couple of months. Also the blackheads that I resisted squeezing out eventually came out on their own over time.
Now even after several months, my problem areas (along the chin/jawline) still have such deep milia that I am still purging. I get one new pimple every week from these coming to the surface. Since I am very fair and scar easily, I've had an obvious red spot somewhere on my face at all times at different stages of healing. I would have been ok with purging for 2-3 months and looking terrible, but at least all my spots would have healed at the same time. Now this whole process has been drawn out much longer than I would have liked, and it's going to take even longer for these acne spots to go away.
Another point to make is that I began using an AHA toner a couple of months ago before applying Differin at night to A) help clear up my spots faster and B) increase the effectiveness of the Differin. This seemed to help a LOT. I noticed that my milia/blackheads were clearing much faster when I added this.
I am now done with my tube, and I decided to upgrade to RetinA Micro. I can already tell a huge difference in my skin already. I've had a few deep blackheads on my cheeks that have been there forever that are juuuuust below the surface of my skin. With one week's use of RetinA, they are already coming out. Those suckers have been there 8 months!
So would I buy Differin again? No. Now that my skin is used to retinoids, I feel like I need something stronger to achieve the results I want. I don't regret using it at all since it was the best choice when my skin was super sensitive, but I probably could have switched to RetinA a few months ago and been just fine. I do, however, recommend it to anyone whose skin is super sensitive or for someone who is trying a retinoid for the first time.