Today is everyone's last chance to get this collection, at least brand new and from the eShop, so I want to talk about what it was.
Super Mario 3D All-Stars is a compilation of three games: Super Mario 64, Super Mario Sunshine, and Super Mario Galaxy (its sequel is sadly, and strangely, absent). Also included are digital soundtracks you can listen to, but they're only in-game so you can't put them on an external music player.
Let's get this out of the way: the collection itself is barebones. In terms of extras for this collection you get a menu to select which game you want to play, which soundtrack you want to listen to, and that's it. When you're in the middle of the game you can press the - button to return to the main menu at any point. As a celebration of Mario's 35th anniversary it's underwhelming, but as a means to play its included games on the Switch it's serviceable.
Speaking of the games themselves, they're outstanding and have stood the test of time wonderfully. These are also technically the best official releases of these games so far thanks to their upscaled graphics, widescreen support (except in Mario 64), and some toggleable options for controls. Super Mario Sunshine also has GameCube controller support, so the option to play it with its original controls is there if the Joy Cons or Pro Controller aren't your thing. As long as you don't expect any substantial new content, you'll be happy.
I have to mention Super Mario Galaxy specifically. It's one of Mario's best games and while it is even better here, it does have some quirks worth pointing out. In the original release, it used pointer controls by pointing the Wii Remote at the TV screen; to adapt it to the Switch, the pointer uses gyro controls instead. If it gets unwieldy, resetting the pointer is as easy as pushing the R button. Do avoid playing this game in handheld mode if you can help it, because tilting the entire Switch for motion controls and having the pointer controls being mapped to touch screen inputs is very clumsy. SMG also uses the pointer for menu selections but not button inputs, which is not only a relic from the Wii era but also a glaring oversight, so keep that in mind while playing.
The version of Super Mario 64 that's included is the formerly Japan exclusive Shindou version, which includes rumble support. Backwards Long Jumping has been patched out of it, but unless you're a speedrunner this won't really matter to you.
In conclusion, this is an acceptable collection of three great games which, in my opinion, is a bit overpriced for what it was. If you didn't get this collection, you aren't missing a lot unless you wanted to play these games on the Switch. But hey, maybe that was reason enough to get it. Only time will tell if these games get individual Switch re-releases.