I've played quite a bit of it. I didn't hate Island Tour though, it was pretty luck-based but still had great minigames and some funny upsets with good presentation, so can't really call these games garbage and I'm a bit of an apologist I guess.
Star Rush does have less minigames, but that's less noticeable than the repetition of boss minigames, which there's only 12 of but you play 3-5 a game. Those games are interesting though because the main mode, Toad Scramble, is all about building your squad of characters and it's cool they made games that support up to 11 characters and are also able to be dropped-in mid-game by people racing to the boss location. You can probably tell from trailers and that description that it's a much different formula, so it's hard to describe if you'll like it, but it definitely offers alot more choice and strategy than previous games even if there's decent luck elements. The minigames are lesser, but the board part is more interesting this time and compensates for that.
So yeah, that's probably why the sentiment is more positive - more strategy in items, picking recruited characters in your squad for specific diceblocks, moving on a grid, using items, balancing coins and stars, etc. You can check out this funny GameFAQs thread - most of the analysis is a bit moot because the game still has large luck components, but there's actually a semblance of strategy here:
http://www.gamefaqs.com/boards/191663-mario-party-star-rush/74555447
The other modes are pretty hit and miss, yeah, most only qualify as novelties really. Coinathlon only has 3 minigames per game but it's designed that way, to escalate and be over quickly. Balloon Bash is interesting but mostly as fun as amiibo Party. The rest of the modes are pretty much minigame-tier, alright but nothing worth writing about.
So yeah. Decent game. Interesting gameplay you haven't seen before. Some repetition. Some luck. Some dumb modes. If you want a good time with friends it's not a bad choice, I think the sentiment is it's "better", or at least more interesting than Island Tour and MP10. Having to download the guest edition beforehand is a bit of a pain imo though.