There are always risks to every procedure but miconeedling or Dermarolling is a good way to decrease the appearance of acne scars. Using PRP with needling is even better.
Acne scars require an experienced practitioner
With any invasive procedure (such as needling) infection, bleeding, bruising, lack of improvement, and worsening of existing scarring are risks.
Several treatments are required with the needling method to see improvement, but how much improvement you'll get depends completely on the type and severity of your scarring. Needling may not be your best or only answer.
Acne scarring is one of the most challenging problems to improve, but it can be improved. Improvement, rather than erasure of scars, is the only realistic goal. There is no one best method for acne scarring. Often many different methods are required in combination to improve acne scarring, depending on the type and location of scarring (boxcar, ice-pick, rolling, etc.).
Surgery, dermabrasion, punch grafts, subcision, laser treatment, TCA CROSS, and needling are all methods that can work, but it's important to find a physician with considerable treatment experience with acne scarring. Beware any physician who only has one tool or one answer... you will likely need a combination of treatments for maximum improvement.
Acne scars are virtually impossible to remove and it is unfortunately all too common that treatments fall short of patient expectations. I would highly doubt that you could expect 50-70% improvement because this degree of change is almost impossible even with lasers and facelifts on acne patients.
Needling treatment for Acne Scars
Every single medical or surgical treatment has associated risks in addition to the presumed benefits. When the skin is broken you automatically take on the small risks of infection, bleeding / bruising and additional scarring.
Without a photograph it is impossible to cogently advise you on what can / should be done in your case. But the needling treatment / or as we term it SUBCISION involves cutting tethering scars that pull the skin surface down creating visible dimpling. It is usually done in combination with placing a filler in the space where the scar was located to push the skin up and keep the scar ends from reconnecting. It MAY work for you on the other hand so can Erbium laser resurfacing. (You may want to check the Sciton Profile or Joule on YouTube and see what it can do. It may very well be the answer to your problem.
Dr. P. Aldea