Ok, guys, stupid question, if I may.
While the game has caught my attention with the fanfare and at a $20 asking price, it appears to be a 2-D platform game? The last game of this type I played was probably during my teen years, Ghouls & Goblins, if I recall.
What's so great about this game? Serious question. Heck, for $20, I may just pick it up on general principle.
The first game (Hollow Knight) is one of the most acclaimed Metroidvanias because everything that makes a game fit into that category, it does exceptionally well. The platforming is tight when you get the hang of the game, but there's enough room that you can utilize tricks and later power-ups to platform faster or reach areas that you normally wouldn't be able to reach until much later. There's areas where a ledge is just a little too high to reach, but if you are good with certain tricks, you can reach that ledge and grab items earlier than you normally would be able to. Most of the tricks revolve around the combat - particularly the "pogo" attack where you use a downward slash to bounce off the enemy head. Doing so can give you a boost in height and get you to those ledges that are just a bit too high. You don't see these types of things often in platformers and Hollow Knight (and Silksong) do it incredibly well because the developers intended for skilled players to reach some places earlier than before.
As for the combat itself, it's very polished. In general, the movement and combat is just incredibly tight to the point where if you get hit, it's 100% your fault - much like a Souls game. It also draws aspects from various Souls games in that if you die, you lose all your currency until you go retrieve your body where you died and if you die before you reach your body, all your currency is gone. Also, much like a Souls game, the game is difficult. The normal enemies can provide a fair challenge, but the bosses are where the combat truly shines. You do have spells and a heal that must be channeled, but in order to cast them, you have to power up your "magic" meter by hitting enemies and your offensive spells as well as heal use the same meter. So you get to decide if you want to go for a high damage spell or save that precious magic for a heal and if you do decide to cast a spell, you have to physically hit the enemies multiple times if you want to heal. It makes for a very high risk/reward playstyle.
However, all the platforming and combat aside, where the game sets itself apart from the rest is the story and atmosphere. I went into the first game expecting to play a new Metroidvania but I ended up getting sucked into a world that I couldn't break away from. I had expected to load it up and check it out for an hour before bed, but I legitimately stayed up the entire night playing the game because I honestly didn't even look at the time until the sun caught my attention coming from my other window. It's been a long time since that happened.
The last thing I'll say is that it's definitely a game that's earned its praise and it's even more impressive when you learn it was made by a team of three people. If you're a fan of Metroidvanias and can stand a 2D Souls-like game, grab the first one immediately and then come back to check out Silksong.