Alright, I'm on my 7th challenge now. I've unlocked a new ball, a couple of accessories and outfits. Beat 3 tourneys and 3 one-on-one matches, so I'm getting there. No new characters or courses yet. I like the
feel of Mario Golf better, if you know what I mean. Just the satisfaction of the controls, and look of the special effects, the sound effects for the various types of shots and effects, etc. Not by much, and it's by no means a big deal. HSG, so far, is definitely a VERY close second in that sense.
But I am digging the main game mode (Challenge) in HSG a LOT more than the single player in MG:TT. I've still barely touched it, I realize, but only time will tell if it can match up to the g-dly MG GBC and MG GBA, however!
Freakin' awesome game, regardless.
Edit - Regarding the various one-on-one matches. Is there only 1 base model each for male and female characters? WTF? Hell, I'd take generic, but different chars over these "unique" but cloned chars any day!

I'm on my 4th one-on-one and all of the challengers look identical!