I have a Samsung Galaxy S4. It's my first Samsung phone, and it hasn't been bad. I'm not a fan of the TouchWiz overlay that Samsung puts on top of the Android operating system, but it has served me well. However, I've been waiting patiently for a few months now to get the update to Lollipop and it still hasn't come. So, rather than continue to wait, I decided to install a development version of a custom ROM called CyanogenMod. In all honesty, it was the best decision I think I've made so far in 2015.
CyanogenMod is pretty close to being the stock Lollipop experience. No TouchWiz, no bloatware, no middle layers between you and the operating system. It is wonderful.
So, why is is so much better. I'd be lying if I didn't admit that it just looks better. It really, really does. I'm not one who gets caught up in form; I want functionality. But the look of Lollipop is simply wonderful.
The real benefits though do come in function. For example, the built in ability to have trusted devices and trusted locations. If my watch is connected, it knows that I must nearby and so unlocks my phone so that I don't have to put in my pattern lock. If I'm at the house, it knows it, and I don't have to put in my pattern. This feature alone has made my wife somewhat jealous.
Additionally, the way notifications pop up on the screen at the top when you are in other apps. They poke down, let you see what is going on, but without being intrusive.
Multiple profiles are available if you're sharing the phone with others or want different setups (work and personal).
Battery life is better than what it was prior to switching to CyanogenMod.
Now, the recent apps feature shows your Chrome tabs mixed inn with recent apps, a huge plus for me.
The status bar and navigation drawer are even more useful.
The change from KitKat to Lollipop was one of the biggest changes I recall seeing on my phone. It's wonderful.
So, if you're anxious, give CyanogenMod 12 a try. For the Galaxy S4, their nightly builds are good enough to be your daily workhorse. At least they are for me, and I feel like I ask a lot of my phone. Yeah, it will void your warranty and all that business, but, it is completely worth it in my opinion. Lollipop really is that good.