Well, as a long-time player of the Pokemon series from gen 1 of the Gameboy Color to gen 8 of the Switch,
Certainly, it didn't come out as everyone expected.
It has its good and bad points.
Graphics
Let's start with the most well-known aspect that almost everyone looks at nowadays, it's not good. For a game on the Switch, I expected something better. They could have done a better job for sure. Essentially, they took the designs of the Pokemon from Sun and Moon and put them there hastily. The trees look very bad, as well as the ground. It's definitely one of the downsides of the game when you're playing on a console and expect something better than this.
Gameplay
Menu: quite easy and simple, easy menu.
Story: you don't have one rival but three, which makes it more interesting with nice battles. However, the only annoying thing is your main rival who talks too much, and at some point, because you encounter him several times, it becomes tiresome and annoying. The legendaries are interesting, especially Eternatus, which was the Pokemon that introduced the whole Dynamax concept to the Galar region.
Wild area: the wild area is quite beautiful to explore, and you can catch 90% of the Pokemon there depending on the weather. You can spend endless hours there without realizing it, and you can catch Pokemon that already know egg moves. If you find a Pokemon shining with an aura around it, catch it.
Cities: all the places with gyms and everything you pass through are very beautiful, and it takes quite a bit of searching because everything has different items.
Battles: very nice. As a VGC player, I play more Doubles, which are faster and require better setup. As for Singles, they are slower than Doubles due to stall Pokemon. As for the atmosphere, it's awesome. You can choose the theme you want to listen to while playing, and in some battles, you can hear the voices of the crowd cheering when you Dynamax. It's quite nice!
Trades: classic, but it seems a bit faster, although sometimes the wait to start the trade when selecting the Pokemon takes a little longer. It also has the surprise trade, basically a wonder trade where you choose a Pokemon you want to send, and the system finds someone who wants to do the same, and the trade happens. Very useful for completing the Pokedex.
Breed: you reach the first nursery very quickly after the first badge, and you can start immediately. It's much faster, and with a charm and a Flame Body Pokemon, it only takes a few seconds.
Max raids: the coolest element in the game. In the wild area, you find the so-called dens, which depending on the color of the beam, red being common and purple being rare, some Pokemon have more shields than others and are quite difficult to defeat at first. You can either join with online players, but you need to have friends on your Switch who are playing, otherwise, you won't find people. Another option is to go offline and only play with bots, which will be much more challenging.
Dynamax/Gigantamax: it's really cool to see them become huge and powerful. The difference is that Gigantamax changes the appearance of the Pokemon and becomes even stronger, with different effects moves.
Comms: The comms are when you want to connect online to find other players, it has many issues, sometimes it doesn't show your friend's raid if you have planned to play together and you need to log off the comms and log back in, and overall it is quite slow. I consider it the biggest problem in the game, especially for those who play online.
Sound: The sound quality is quite good with nice music and clear audio.
Overall, it is very good but fast compared to other games and much easier. For those who have played the old games, just know that it is very easy to finish the league, etc. For me, the game needed another year of work, but it doesn't mean it's bad, on the contrary, it is very good, it just could have been much better.
Know that if you get any version of the game, you can find exclusive Pokémon through trades with friends or online through surprise trades. Or you can search on Reddit for codes that give you exclusives from the other version.
And now they announced the DLC for €30, which is good because you don't need to buy another newer version like Ultra Sun to play the whole game again with small changes. They will add 2 new wild areas and dens for raids, as well as legendary Pokémon raids!