I haven't been impressed with any of his material since 01-02ish, and even then I thought it was getting way more hype then it deserved.
I absolutely hate how idolized he is, mainly from the American club culture. I will even say I was part of that cult at one time.
Pic to prove it, I have the Chewbacca shirt on :P
What happened I think is that people started just liking anything that was released by him, because it was Tiesto. The songs didn't need to have any substance, because everyone would buy it on its name.
He needs to re-create stuff like Kamaya Painters - Summerbreeze/Endless Wave/Wasteland tracks.