Although there is sadly no golf in the day one package of Nintendo Switch Sports—we will have to wait for free DLC later this year—there's a decent selection of stuff here with fun times to be had in both local and online multiplayer.
--
Thoughts on each sport (more comments on the game as a whole below):
The "B"s may be the best this game has to offer. I really enjoy Bowling, back from Wii Sports with a fun new online mode with a bunch of players playing simultaneously, where the bottom half of the pack gets eliminated every few frames. There's also a side mode that adds obstacles to the lane, but it feels pretty underwhelming.
Badminton is both the one of the most exciting and the easiest to pick up and play intuitively. It's fast-paced and precise enough in a way that feels good, without getting too frantic. I'd suggest starting there.
Soccer / Football is the flop of the package due to painfully slow movement. It does have fun moments with its motion aiming and a decent comeback mechanic of a golden ball worth two points. Still, it feels like they tried to replicate Rocket League with the large ball and goal area, but didn't quite get why it was so fun.
Volleyball can feel like a bit of a mess, shuffling players around on the fly between various positions and control schemes. I don't think it works quite as well a pick-up-and-play party game as the other sports, but once you get used to it, it's not bad.
Chambara (sword fighting) was an unexpected success, with a nice element of mind games. Blocking and getting past the opponent's blocks feels good. Three different selectable fighting styles add some extra variety. While the other sports tend to drag on if players are tied, this one has an exciting sudden-death mechanic that works well.
Tennis feels like Wii Sports tennis, a simple, a fine time that streamlines the real sport a lot. Could stand to punish players a bit more for spamming swinging the racket around. I'd just stick with the similar-feeling Badminton—bit of a shame that two of six spots are taken up by similar games.
--
While the game is best in local multiplayer, online mode is pretty good, letting you queue up for 3 sports at a time for quick matchmaking. I think the netcode on Soccer is a bit wonky, or maybe they just need to match people with similar internet connection strength together. Other than that it all works great.
You must play online, actually, to unlock customization options for your character. These are done via limited-time sets of items where leveling up lets you randomly get an item from a set. The selection early on is faaar too limiting, but overall I don't mind this system to give a tiny bit of extra longevity to the game. You can also play as a Mii if you're feeling retro (sorry).
Buying the game physically costs $50 instead of $40 and gets you a leg strap similar to the one included in Ring Fit Adventure. Don't bother unless you just want a physical cartridge, especially if you already have Ring Fit. It's seemingly only used in one boring side minigame for soccer, by no means needed. $30 may have been a better base price for this, but the free DLC should bridge the gap.
Not much else to say, it's not an outstanding game, could be better, but it is what it says on the box. If you already have better stuff like Mario Kart 8 and Mario Party Superstars (review), and want a fun little motion-controlled sports game to add to the rotation when friends or family are sat around the Switch, or just to screw around with by yourself for an hour every once in a while, this is not bad by any means.