AnandTech reviews Android 5.0 Lollipop, and concludes:
I think Google really hit the nail on the head with Android Lollipop. It evokes the same sort of feeling that the release of iOS 7 did, without some of the negative experiences that followed. Getting a brand new interface is always exciting, as it can dramatically change how it feels to use your phone. Moving from KitKat to Lollipop still provides you with a familiar Android experience, but it almost feels like getting a brand new phone in a way. There’s a brand new UI, and big improvements to performance. But unlike the upgrade to iOS 7, Android Lollipop hasn’t plagued my devices with application crashes and other bugs. In fact, I haven’t really noticed any significant bugs at all after upgrading to Lollipop, which says a great deal about the work Google has put into testing to make sure things are stable.
My experience with Android 5.0 Lollipop on my Nexus 5 have been almost entirely positive. It’s still Android, and it won’t magically draw people away from iOS, but as a whole, it’s a huge leap forward over what came before.