I don't think his compositions are that impressive compared to music written by actual classical composers. I've always compared him to Yann Tiersen, since they both write "mainstream classical" music. It's easily accessible for the mainstream who don't listen to other classical music. There's nothing wrong with that, but from a classical viewpoint his music is nothing special, just a mediocre copy of Debussy. Einaudi to classical composers is like Korn to Dream Theater, both Korn and Dream Theater are metal bands but the latter just has so much more musical depth to it. The only downside is that DT harder to get into for the mainstream.
So, to answer your question, I'm not a fan of his, but I think his music serves as a good entrance into classical music.