Touchwiz is perfectly fine for me. I use my phone for both business and personal use. My primary needs are communication - Email (more than 5 different email streams using Touchdown, Gmail, and K9 as clients) - Messaging (SMS for business rarely use it for personal, Hangouts used for both business and personal), remote access (RealVNC, FTP, SSH/Telnet, VPN), Health, Weather (monitor my weather station, office environment, data center).
There are a lot of Touchwiz features I don't use, I simply turn them off, but they are there if I need them. A perfect example is that while I've had my phone since Oct, I have not used MultiWindow at all. I just turned it on last night as I found a real use for it.
Reliability. My phone works. Not sure why some others don't' but mine works great. Stock 4.4.2 Rooted rom. GPS, battery, no repeat reboots etc..
I have seen things cause issues, indicating they are the problem not the phone like Greenify, certain adjustments via Wanam Exposed. I use it for a lot of things, but some things I tried did start causing problems, slowness etc... I just turned those changes off.
Battery Life. This is the first smart phone that I have not gotten a secondary battery for. I easily get 14hours with room to spare and I am well prepared to charge if really needed (had a 27 hour stint on day at work for a major upgrade, just plugged it in).
Is it perfect, no... never seen a smartphone that is.. but as far as the ones that I have had, it is the best I've used so far.
I may not use my phone like a lot of you, I don't have time to play with loading different ROMs or making massive changes to the phone both due to lack of time and more importantly, this phone has to work for primary functions or it is useless to me.
It seems to me that if you don't like touchwiz, you root and load a lessor Rom with what you do like and be happy with that. Should they remove touchwiz, don't see that happening and still having the features that most owners use.
Note, most owners, don't know about rooting, they never heard of XDA and have no clue that you can do some of the things you can with the phone. They just use it and think it is great because they don't know of anything else.