A well made game which definitely is a favorite!
Awesome, the idea is great, but I've always hated golf flash games but loved golf TYPE flash games :)
What I liked was the graphics. They made me, let's say, happy. They we're simple but colorful. If you make a sequel, leave the graphics as they are; they might not be very complicated, but the simplicity of them make them great.
The idea, as said is great, and as well performed great. I really think the physics were well made and bug-free.
Another plus, a major one, is the achievements and unlockables. They give the game a feeling that there's been a lot of work put on it, while giving people even more fun! I've always liked this sort of thing in games, the fact that you did put it in your game will give you a plus, again!
The medals gave you a picture of how well you made while you played the round, great here too.
And I must give a huge plus for something as awesome as a level editor, it definitely does give the game a bigger replay value. The editor was well performed and easy to use, but I still think some instructions could be added there, as you did so well for the game itself.
Ideas for improving? Well, highscores would do awesome, as well as a bigger screen sometimes, thinking about the level editor.
In overall, you did a great job. This game definitely gets a place in my favorites, while I'm about to play it many times, while bored and while not!