Well, every game that runs at higher than 1080p on PS4 Pro is super-sampled down to 1080p on a 1080p tv/monitor. This results in a cleaner image than you would get playing the same game on a normal PS4 or PS4 Slim. It's basically like extra anti-aliasing. Additionally, certain games offer other improvements on Pro, a few offer high detail modes, which enable higher end settings from the PC versions of the same game instead of higher resolution, a few offer higher framerate modes (though very few games have high framerate modes that actually hit 60 fps), a few have minor upgrades like improved shadows or textures over the standard PS4.

On a per game basis, some games have a choice between resolution mode and framerate mode, and fewer still have a choice between resolution, detail, and framerates modes, you have to pick those in the in-game options menu. Other than that you're good. Best way to compare the side by side difference is the digital foundry analysis for each game, they usually do a side by side between standard PS4 and PS4 Pro and between standard XB1 and XB1 X somewhere in each analysis video, if you watch their analysis video on a 1080p tv, it gives you a good idea of what the cleaner image quality produced by supersampling actually looks like. It is a noticeable difference to me personally, though not a huge difference. 

Yeah, you're probably better off waiting. I'm willing to bet that Pro will be on sale for $330 or less on Black Friday, and you may even be able to nab the RDR2 Pro bundle for that price on Black Friday if you're lucky and stock lasts until black friday. 

Not really. Something vague like 4k support or something.

This is the most complete list out there:

https://www.resetera.com/threads/all-games-with-ps4-pro-enhancements.3101/

It details all the games with PS4 Pro support (official, PVSR and boost mode) and its enchantments.  Most list on the internet are outdated.

You can now play Ni-Oh at 1080p 60. Welcome to the club!

After enabling boost mode, that's pretty much it. Everything else is on a per game basis. Boost mode will have unsupported games running at higher frame rates if the game supported unlocked frame rates to begin with. With PS4Pro supported games, the most common advantage for 1080p players is just down-sampling from higher resolutions. You'll notice less aliasing and better textures because of this. Loading is also usually a bit faster on the pro.

EDITED

You can let boost mode on, always and if I were I would not activate supersampling in the system options, more on that on that post.

Basically all PSVR games benefit from Pro. Difference can be very noticeable for those that could test both consoles. Most games (if not all) have a higher resolution and some have on top of that (or not) better effects and increased framerate (90fps or even 120fps instead of 60fps).

While most games will run better on Pro, some of them will run targeting 60fps instead of targeting 30fps like Shadow of the colossus, God of War and the last 2 Tomb Raider. But others games benefit from big boost in performance for instance in Monster Hunter World (50% higher performance on Pro) if you play at 1080p without enabling supersampling in the system.

Also old games greatly benefit from the Pro like for instance Assassin's creed Unity that now runs at a solid 30fps instead of ~20fps in crowded areas.The talos principle for instance often gets a bonus of 15fps on Pro.

I would advise you not to activate supersampling in the Pro options, cause some games like Monster Hunter World, The Witness (4xMSAA instead of 2xMSAA) or even Gran turismo play better at 1080p (8xMSAA at 1080p on a Pro, MSAA is much lower at 4K) without downsampling. Image fidelity is increased by some developer in that mode, and you'll still get a native image or higher framerate.

Downsampling is way overrated and was used as a checkbox feature in the Pro / XBX console war. But IMO it's not worth it. I much prefer having higher (or more stable) framerate, and a native image (so somehow sharper). So in short:

- Keep Boost mode on
- do not activate supersampling

I also found the OS was faster.

I disagree; it depends of the game, if boost mode or supersampling are better.

Boost mode should always be On by default and it only works on non-enhanced games. the rare (maybe one or 2) non enhanced games that had problems with that have being patched now.

And yes I am not a fan of supersampling cause I always will prefer a native image on a 1080p screen. If I had a 4K screen I would surely prefer playing at 4K (except when a 60fps mode is available of course).

The real treat comes from HDR. I bought a new 4k HDR TV on Black Friday last year. The resolution increase is nice, but it just isn't near as big of a deal as the improved coloration of HDR.

With that said, when you do take the plunge for that TV, make sure to check out the reviews on rtings.com. also, make sure to read the full entry for the TV that you end up buying, as they have recommendations for various settings to get exactly what you want out of your new television. In my opinion, their reviews are far better than anybody else's.

Welcome to the Pro club.