I'm not hugely into fighting games in general, but I was interested in Arms on Switch since it was one of the few first-party launch-window releases that was an entirely new IP. The game has a bright neon aesthetic that feels very similar to Splatoon, although it does have its own identity.
I watched a fair amount of footage of the game before it was released, but it was hard to get a sense of the game's depth. The game is pretty easy to pick up and play, but it definitely takes time to gain proficiency. Like many fighting games Arms relies on punches, dodges, blocks, and grabs, but as with other fighting games it takes time to get used to the mechanics and the timing of the actions and how to best react to a given situation.
Each character has her/his own special abilities, and there's a wide variety of arms to choose from. You can equip a different arm for the left or right, and although each fighter comes with three unique arms your fighters can use the other fighters' arms after you earn them in a punching targets minigame. I spent most of my time playing as Spring Man (a balanced fighter), Ribbon Girl (who can jump four times compared to the usual two), and Helix (who can stretch its body to avoid attacks). Some arms seem much more useful than others (slow ones in particular seem hard to use), but I suspect that with the default arms at least that the game has been pretty well-balanced. The game doesn't fully explain the unique mechanics of the individual fighters and arms, but there are resources online to help fill in those gaps.
The game has a standard single-player mode in which you battle a series of fighters with the useful addition that you can suspend your progress at any time and resume later. The multiplayer mode puts you in a room and shuffles the participants between various modes that include standard 1 vs. 1 fights as well as a basketball mode (which focuses on grabs), a volleyball mode, 2 vs. 2 fights, and 3 vs 1 co-op fights. Like Splatoon the game has been rolling out free new content, including three new characters so far, the addition of badges (in-game achievements), and a new Splatfest-like mode called Party Crash. The various extra modes are entertaining enough, but the core game has enough depth and variety that I much prefer just playing standard 1 vs. 1 fights.
After playing Arms for a significant amount I've definitely improved, although I'm still a long way away from being truly adept. Arms feels like a breath of fresh air compared to the glut of 2-D fighter series, and even without the additional content the game is packed with personality, fun, and challenge. I'm generally attracted to new IP so it's not too surprising that this is my favorite Switch game yet. Although Arms isn't as immediately satisfying as a nostalgic favorite like the Smash Bros. series, I'll definitely be picking it up again whenever the next Party Crash event rolls around.