I did have experience with Sylvan; although it was years ago. I can't imagine it has gotten anything but better!
My third child has a mild case of ADD (not the hyper part) and has struggled all his life with Reading. Despite the good intentions, it was duing his second year in school that the educators determined that phoenics was not the way to teach Reading. Whether this contributed to his difficulties or not is anyone's guess. However, during his pre high school years, it became critical and there was the threat of his being held back, so through research I learned about, and investigated Sylvan. He attended for 6 months and it was the best money I EVER spent!
He graduated from high school with his class, was never held back, though he did receive remedial services through the school system. Though he graduated he only had a 6th grade reading level which would have been worse if not for Sylvan.
He is 26 years old now and it has been many years ago, but as I stated in the beginning - I can't imagine that Sylvan has done anything but IMPROVE and get better! They are kid focused and oriented.
Good luck! I hope you have as positive experience with Sylvan as I did.