So I've been playing with the s20 all day. I can say, it's totally been worth the upgrade given I had an s10 to trade in. The best upgrade being the camera to me.
The layout of buttons is much better. I do miss Bixby button because i remapped it to be a pause/play button and flashlight toggle. But having no buttons on one side is great, and the ergonomics of the buttons being lower, and fingerprint reader being higher is all great. One handed use is much more comfortable and the phone feels great. I prefer the narrower but taller design. The glass wraps around the back of the phone more so in your hand you don't feel the metal frame of the phone as much. It took the great feel of the s10 and just upped it a bit. The camera punch, although I prefer it in the corner, is substantially smaller and the difference is more than I thought it would be based on watching videos.
My goodness do I love the camera so far. I honestly hated the s10 camera. It's smoothing plagued every photo I took, and I just couldn't stand skin and fur looking like smoothed out clay. Hair all blended together and colors washed out. The s20 is sharp, and colors are so punchy. It really blows the s10 out of the water and returns the crispiness that I haven't seen since my s8. The colors are so punchy while remaining realistic. The s10 had many colors and tones seeming washed out, and the s20 kept them crisp but also more dynamic. The s20 also had better edge detection with portrait. The camera is the biggest upgrade imo. The only complaint I have for the camera is that I've had some photos seem to handle shadows poorer than the s10. Shadows being wayyy darker than they aught to be when shooting indoors near a window, where as the s10 kept everything well lit without overblowing the brights.
Here are some comparison shots I've set up. Sorry they're in separate folders on my imgur. I didn't want to move them around in ways that degraded the quality, so this seemed the best and simplest solution.
120hz is great. It's not worth upgrading for alone, but boy is the phone snappy and pleasing to scroll around on. Definitely a non gimmicky feature. Many reviewers falsely stated the phone must be in 1080p to go 120hz. You can use the FHD+ and this is the resolution I used on my s10 so I couldn't care less. Unless you look for the differences by unnaturally getting super close to the phone to inspect the pixels, you won't notice a difference. The display is great.
It's been pointed out to me that I was wrong about the resolution, as FHD+ is 1080p resolution.
I never used haptics before much, so my opinion may be skewed, but in prep getting for this phone I've had haptics turned on on my s10 for the past 2 weeks. I can confirm the s20 feels way more precise and less sloppy on the haptics than the s10. I may be keeping them on for the first time cause it does feel good to type with. The s10 felt like the vibration lasted longer and less... tight, I guess. I did play with intensity and duration on both phones and stand by s20 being superior.
This is my only complaint. The s20 sounds worse. No doubt. It's tinier like the aluminum soda can type sound. The high end is more sloppy and rattly, where at the s10 sounds very full and even. The highs on the s10 don't blast your ear out or sound cheap. The s20 reverses this unfortunately. It's not, "blast your ears out" bad, but it's certainly worse. It's still good sound, and achieves high volume, but it's less clean and less balanced than the s20 for sure. Highly noticable listening to a podcast with lots of talking.
I am keeping the upgrade for 1st the camera, 2nd the screen and snappy feeling, 3rd the better hardware(ufc 3.0 & new chip) and design (ergonomics). Camera is crisp and doesnt smoothe like the s10. I'll tolerate the speaker degrade. Oh, and the battery charges hella fast. I'll edit in a few days to report on battery life if this post has any attention.