- The things I like best about the game:
* The QOL features of this game are fantastic. Just being able to see your team from opening the menu and being able to instantly set a new Pokemon as the lead with Y is a game changer. Thanks to things like mints, EV-resetting berries, ability patches/capsules, and hyper training, you can actually make your starter and in-game team competition-ready. You can catch a brand new Pokemon and have it ready for battle in an hour or so (depending on how much money you have).
* The story and characters are better than previous Pokemon games by a longshot, in my opinion. I don't want to spoil anything, but I actually really like pretty much all the characters in this game.
* It's really fun to hunt for Pokemon with marks and different sizes. Pokemon of the same species can vary noticeably in their size, and giant and teeny Pokemon can receive a special mark for their size. I've personally felt as though shiny Pokemon have lost some of their uniqueness over time, so I appreciate being able to further customize special Pokemon with things like marks and sizes.
* The Item Printer (an item in the Blueberry Academy of the DLC) is awesome. It actually lets you get apriballs at a reasonable rate compared to sword and shield's Cram-O-Matic (at least in my opinion). There's also an update to your zoom function that lets you see at a glance the gender and size of a wild Pokemon and whether or not it has any marks. This is amazing (if you care about that kind of thing, of course).
-The things I like least about the game:
* The framerate is frankly unacceptable and there's moments where the game struggles with noticeable lag (especially the Casseroya Lake area).
* There's not really much in the way of single player post game. Your only option is shiny hunting. Otherwise, there's raid battles (once in a while they have special limited time 7 star raid battles to obtain otherwise unobtainable Pokemon) and PVP. If you enjoy those things, then you'll be happy!
* Dexit
-What makes the game stand out:
In spite of the game being open world, it's actually not THAT dissimilar to a traditional Pokemon game; there's essentially just really big routes with no tall grass. One good extra thing I can say about it is that due to the nature of the game being more open in terms of the order you can do things in, it feels less "railroady" in my opinion than older games. You are not constantly getting interrupted by a friendly rival or adult gently telling you where to go next. There are a lot of cutscenes, but they happen mostly when you approach an area marked on your map in relation to one of your quests, so it doesn't seem as much like an interruption to me. In general, this game feels less like a heavily curated experience unlike some of the later games (Sun and Moon are very guilty of this in particular).
-Which new Pokemon is my favorite:
Hydrapple! I loved it so much that it inspired me to try the games out after staunchly refusing to play them for a while. I don't regret waiting so long to outlive the more troublesome bugs and glitches, and neither do I regret buying the games. After all this time I have to sheepishly admit that I really like Scarlet and Violet.
-How bad are the bugs and framerate problems:
The bugs are not really so bad anymore; at any rate, I never ran into anything particularly noticeable.
The framerate can be pretty bad, though... it's embarrassing to see trainers flicker in and out of existence when running through towns and the stop-motion animations when you get far enough away from things. Plus there's the bad lag that happens now and then. It's... liveable, but pretty obnoxious. Thankfully it's not always like that.
-How are the raids?
I find the raids to be a BIG improvement over the ones in Sword and Shield. They are still kind of slow due to animations, but overall I find them much more enjoyable. NPC partners are now no longer strictly an embarassing liability. Raids are quite rewarding as well, giving out herba mystica (necessary to make high level sandwiches that help with things like shiny hunting), level up candies, mints, bottle caps, and other such goodies. Your mileage may vary of course, but as somebody who HATED the raids in Sword and Shield, I actually rather enjoy Scarlet/Violet raids.
The only raids that might be difficult to solo are 6 and 7 star raids, but I have heard that almost all 7 star raids *can* be soloed if you had a mind to do so. You may need to look up a guide for those, though.
-How do you shiny hunt in this game?
The shiny charm still exists, as does the Masuda Method for hatching (although breeding in general is just a little different; you now receive eggs while picnicing). However, I find that the more enjoyable shiny hunting method involved outbreaks. Every day at midnight, different outbreaks of Pokemon appear all around the world (including DLC maps), with an increased spawn rate for that species of Pokemon. This will last until the following midnight, or until you KO one hundred of that species of Pokemon. If you KO 60, the shiny encounter rate increases. This can be stacked with other things, including sparkling power from sandwiches. There are guides to shiny hunting with outbreaks online if you're interested in learning more. I think it's really fun and satisfying to see the shiny Pokemon model walking around in the wild!
-Can you obtain all the Pokemon including ones not in the game through trading?
It depends on what you mean by ones not in the game. You may have to use the GTS or go to a forum (or use a copy of the alternate version of the game) to fill the pokedex.
There's one Pokemon that requires a Union Circle (multiplayer) to evolve, but you can also find that Pokemon in its evolved form in raid dens, so Union Circles aren't necessary for pokedex completion.