I've played this game last night until pretty late.
+ 8-player Smash is even more hectic than it is in Smash for Wii U, and this is coming from someone who has played it with chaotic mods on virtually any stage. Additionally, it appears that hazards that weren't present on Smash for Wii U are now present here.
+ I love the Kirby bomber enemy item. Easily among my favorite newer items.
+ Character final smashes are very unbalanced, Mario
especially. This is to the point where I think the Final Smash meter is an uphill battle against him. The Mario Finale feels terrible to use in almost every way, a huge nerf from Super Smash Bros. for Wii U as it's more easily escapable and it doesn't kill 99% of the time. I hope a patch later addresses that Final Smash alongside other fairly mediocre ones too.
+ Stage morph can kill your character if it occurs at a bad moment and your character is in a bad spot.
+ You can unlock a Baby Mario and Baby Luigi spirit extremely early in the game

+ Menu UI is utterly a pain to navigate. These are our first impressions of it. I don't like going through extra menus and stuff in regards to the rules (in Smash for Wii U, the saved rulesets due to mods were saved from my last playthrough and I'm content with playing with those rules every time I boot up the game). Implementing amiibo fighters is also pretty annoying in comparison to just plopping them in by reading them from the NFC adapter.
+ Ness's new up air is worse than his old head bonk, especially when playing in situations where it can be easily interrupted such as in multiple player smash. He still feels great to play though!
+ Level 9's and amiibo fighters are still lulzy to beat up.
+ Cinematic such as Yoshi's stampede or Wario's farts final smashes carry over that annoying bug from Smash 4 that you lose your item if some *bleep* performs it on another *bleep*. I hate it to see it unfixed here.
+ Character unlocks are long, tedious, and something I wish I had an option to unlock all of them from the getgo.