My new phone is now no different.
In trying to research what problems can arise if you encrypt Android, it did seem like encryption isn't a widely used feature. But, as I was starting afresh with my phone anyway, it seemed a good time to test it out.
On my phone, out of the box, it encrypted in just a few minutes. I didn't bother running any before and after benchmarks, but it doesn't feel like there's any impact on the responsiveness of the phone.
There are two downsides though.
One is the irritating feature that the encryption password is just the screen unlock password you use. This isn't great. It either means you need a painfully complicated screen lock passphrase, everytime you want to unlock your phone, or it means you'll have a simple encryption password.
That issue discussion highlights that it is possible to change the encryption password, but this requires you to enter a shell command as root. There's an app that adds a convenient frontend to this process, though it still requires root. As the README there points out, watch out: changing your screen unlock code will change your encryption password to this too!
The second problem is that encryption can impact on your use of recovery. ClockworkModRecovery doesn't support encrypted devices. TWRP apparently does, but didn't seem to work with my Moto G; it should prompt for an encryption password, but doesn't and just fails to mount the phone's partitions.
That's not a huge problem for me, but I expect that this is going to prevent my phone from receiving official updates. Perhaps reflashing a manufacturer recovery and updating will work? In the (only slightly inconvenient) worst case, I'll just have to backup everything, do a fresh install, re-root and restore everything.
It would be nice if encryption on Android was more user-friendly, though as the problems aren't particularly onerous, the extra security is definitely welcome.