Performance seems subpar, much like iOS 8. I'm sure some patches will fix things.
Unfortunately, no matter how pretty Android L is, without Google devices having a TouchID like feature, they will always be behind the times.
I'm actually beginning to think Google won't get into the finger-print game. They didn't with the Nexus 9 or the 6, and there doesn't seem to be any evidence in Android L or anywhere else that they'll start adding it (has there?). With the exception of Samsung, who probably did it to say they have it, not even other Android OEMs are incorporating finger-print scanning it seems. LG, Sony, Motorola, HTC, and even the smaller companies like Xiaomi, ZTE, etc., none of their latest flagships from 2014 really venture into finger-print scanning. Correct me if I'm wrong?
Besides, in my opinion, Touch ID is overhyped. It fails more frequently on my iPhone 6 than I want to admit, and many of the other times it does work, it's a little slow. I've already re-scanned my two thumbs multiple times, and the results are the same. I also find that any little body temperature change can make it useless (if my finger's a little hotter or a little colder, for example). Too often, I have to re-apply my print to get it to work.
Worse of all, Touch ID feels half-baked, honestly. I love the idea that Touch ID can bypass my Apple ID password in the App Store, yet every now and then, a pop up will say "in order to continue using Touch ID in the App Store, please input your Apple ID password." That frustrates me and makes me wonder what the point of Touch ID is.
At the end of the day, I might just go back to a pin-code. At least it's reliable and I only ever have to input it once to get it go 100% of the time. With Touch ID, there's always this chance of it failing. Even 1 time out of 10 is too much, but it fails at least 3 or so times out of 10.
I don't see lack of Touch ID as any deal breaker to Android devices. The Nexus 6 has other deal breakers, but not lack of finger print scanner, in my opinion. And I wouldn't hold my breath out for one in future Android devices, but I could be wrong.