Worse than 10166? Zero improvements? ZERO?? Wow, way to pee on my corn flakes. Doesn't feel that way to me since I can do things in this build I could not do before like install apps, launch apps without have the wait bug, instantly launch my music app Groove and play music among quite a few other things. If this build for you is worse, roll on back to 8.1 and wait until fall for whatever phones Microsoft drops. I hope by then, something will be noticeable for you.
But I'm also wise enough to know its the next step on the march to greatness. Ergo, its not done yet and there will be other builds.