What is it lacking exactly
Posted via the Android Central App
If you use or experience in any way the current Touchwiz version you'll know for sure. But just to give you some quick examples;
1-) Quick Settings (incredibly useful for those quick settings tasks)
2-) Limited Quick toggles
3-) No multi-taking or multi-windows options
4-) Vertical Apps drawer scrolling (I know this is personal preference but come on, besides Nexus phones I've had basically all Flagships and some mid range phones out there for the past 4 years and ALL of them use horizontal scrolling not vertical)
5-) S Planner on Galaxies are a great Calendar app and the widgets are even better
6-) Buggy Native Weather App (I haven't been able to even get the Current location weather to work for me where I live, it seems that most if not all people from Puerto Rico are having the same issue).
7-) No native gallery App, sorry but Google Photos is good for backups but not for a Native Gallery App.

Google Play Music player is still too much for us that just need a simple Music Player, Samsung one is simple and great.
9-) No Desktop Grids adjustments, love to use 5x5 on Samsung phones.
10-) No Direct Call, in Samsung phones whenever you have a contact on screen via the Contacts apps or Phone Calls Logs and you bring the device close to your ear it will call that contact.
11-) No Optional Quick Answer or reject by just pressing the icons not swipe needed.
12-) No simple swipes to call or sms, with touchwiz you swipe left to send sms or swipe right to call whenever you have a contact list on screen
13-) No Enhanced Messaging (At least on T-Mobile, I don't know if Verizon added their stuff)
14-) No manual LED disabling - in Touch wiz is as simple as go to Display Settings, in the HTC 10 I needed to download a third party app for that, very annoying during night time or trying to sleep.
15-) When you compares it with the S7 edge, then no Edge functions, great and useful edge features, quick access to contacts, shortcuts available on any screen and a couple of others that I use every time.
16-) Something not specifically related to Sense vs TouchWiz but it must be here also and is NO SAMSUNG PAY.
As you can see, there are a lot of things I can think of, and there are some others more, but I think you have the point already. I know must, if not all, are a matter of personal preferences, but again, you don't know what you are missing until you use them and then move to other devices that doesn't have them. HTC have built their best device ever, but for me is not the best device out there, for me it's a keeper, as I really love it's build and some things here and there, but people saying that Touchwiz means poor performance or lags, it simply means that they really haven't tried latest Samsung flagships, my Note 5 that I used for 5 months never had any issues, my daughter has it now and almost 3 months later it still like the first day I bought it on August. My Wife and other daughter's S7s have been working great since day 1 for almost 3 months now, and my S7 edge is just the same.
Every people needs different things, and there are people that even after using the S7/S7 edge feels that they don't like them and that's all good, there's not a single phone that will be the best phone for every body and that's why Android is so great, so many choices and great options to fit everybody's needs, but I'm just saying that sometimes most of Samsung bashing has been for past experiences and from people not willing to give them another opportunity, take a look at the S7 forum and you will see TONS of other ones that have done it and are saying that Samsung hit it out of the park this time and that they have changed their minds.
So, as you can see, right now I'm a happy camper, I have what I consider the best 2 smartphones right now, but I'm an honest person, I give credits where it's due and critics when I feel I need to, and no, for me Sense is not the best Skin out there and it's lacking in many little things that I consider very important, and once you use them and are used to, it's very hard not to have them. To each it's own, but if it wasn't for Nova I'd returned this phone just days after buying it.