I don't have much of an opinion on golf games in general but I've heard good things about Super Stickman Golf 2, so I gave it a shot. It's a very quirky golf game where the stages are setup to make you use your powerups carefully to get good scores. The stuff around the core game - level up system, equipment, challenges - is also pretty neat and difficult and getting everything is taking quite some time.
Okay, the level up system and hats are mostly irrelevant
You get different golfers and they don't do anything besides cosmetic changes, you also get access to new courses, but that could be unlocked after you beat the previous ones. Why is there an exp system? You get experience when you beat levels, with bonuses baked in for getting gold stars and not using powerups and things like that, but all and all, it's pretty much useless.
Even the hats, most of them don't do anything useful, having blood water won't help anything and slower moving power meter will not matter much, at worst it'll be a nuisance.
How I would fix this?
Why not give meaning to the levels? You could have variable power levels depending of your level (starting with weak shots then being able to do stronger ones) also accuracy, number of power-up uses, strength of some power-ups, who knows! The list of potential stats that could get better are limitless.
You can also buy a few things with real money, such as an experience doubler, but as you might know already, I fail to see why you would buy it for the low value of actual experience in the game. The other things are multiplayer matches and a little meter to show you how strong you hit the previous shot. Weird, that could've been part of the main package...
Also, hats, you unlock them with a lottery system much like Super Smash Brother Brawl and the trophies, the more money you wager, the more chance you have to get a new hat. It's a neat carrot because the hats have at least, SOME uses.
You get money for tons of things, achievements give you money, you can find money in the courses - and getting them all will give you a bonus - and some random challenges also appear to give you a few buxs. I usually try to do them because they are basically related to the number of shots you need to do to win the level.
Otherwise, the game itself is pretty good
You move a line with virtual arrows then a power meter fills and drains until you hit the shot, then the ball flies around, hitting hazards, water, pits, sand and much more. You do that until you get to the green, then your only choice is to putt the ball very gently. Which means that if you wanted to do some tricky shot to get somewhere and fell on the green, too bad, you rarely can get out of it.
Most levels have a recognizable design; there are a few ways to get to the hole, one of them will take few shots but is trickier to manage, the other is more easy but will take more hits. Sometimes you'll need special abilities (such as sticking to walls, freezing water) to navigate the shorter routes and sometimes you'll just need to aim good. And it's hard to know where and how far your shot will go, maybe some kind of pointer would've been nice?