I've recently rooted and installed CM 12.1.
Stock Lollipop seemed ok at first but somehow got progressively worse, the lag to launch the phone app reaching 8 seconds was the final straw, along with having to charge the phone around lunch time :/
The S-Pen, fast charge and the fingerprint reader still don't work, plus the camera is flakey with some camera apps but not others.
Minor issues for me as I don't use the pen, I'm back to only charging when it's convenient to do so - while I sleep, drive, shower, sat at my desk etc... smart lock is better than the fingerprint unlock if you have a smartwatch (as I do) and its not a big deal to change your camera app.
The phone is really, really smooth and lag free (even more so than on stock KitKat). Unbelievably so.
Also noticed that other things seem to work better than they did even under KitKat, my Fitbit has started syncing at first time of asking, the BT wifi app works now where it didn't before & the music controls on my watch are consistently instant rather than anywhere between a 10 seconds delay and a 10 minute (!) delay.
This has majorly put me off Samsung though, I had similar issues with my S3 and said I'd never go back. I did but really won't again.
I'm not a massive Apple fan but what I can say for them is that if an update kills a flagship device (which the Note 4 still is) in that sort of way it gets fixed in days rather than months. I really shouldn't have to install a custom ROM to make a phone that I'm paying a lot of money for work properly.
Reckon it's between an iPhone and a Nexus device when I upgrade in 18 months.
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