I only ever played " Golf " on the NES, so I can't easily draw comparisons to other Mario Golf games. Although, most people have stated that World Tour on 3DS was a jam packed, full game on release. And frankly, I'm not surprised Nintendo went the same route in Super Rush as they did in Tennis Aces: bare minimum first, free trickling of content later.
That's not to say what's currently in the base game is bad by any means, just lackluster in terms of maps and modes. The golfing itself is amazing; golf club variety, golf hole/field variety (from the current base maps), a handful of swinging techniques that aren't apparent right away, crazy curve/arch swings, choosing the way your golf ball lands, ect. And when you put everything you learn from the Adventure Mode into practice, it's so freaking satisfying to swing good shots.
Speaking of Adventure Mode (no spoilers), it's really nice. Nothing absolutely crazy, just a pleasant experience... for the most part lol. Some golfing missions were a drag. Anyways, I could see the devs adding extra content to the Adventure Mode whenever new courses and characters come around. They could be mini side stories with extreme challenge. That'd be delightful.
Unlike Tennis Aces, there's no tourney-style online mode in Super Rush, which is kinda unfortunate to me. Only friend/private rooms and rooms with randoms are a thing. Oh, and I didn't touch on the different golf modes, but everyone knows Speed Golf is the best addition. Fast paced swinging hyper-dash to the hole! It's invigorating! Going back to the regular take-turns golf mode after nothing but Speed Golf feels like time is stuck in a sand bunker.
But yeah, overall a solid Mario Golf game, just pretty content-barren as of writing this review.