These types of open world, non-linear, diverse gameplay, achievement hunting games are the best.
My favorite level was the Link level, because it had the best character, had a boss, had nice secrets, no bugs and a funny joke at the end.
The game had a very well calibrated difficulty, was not too easy but also was not really hard which is important considering it is made after NES games which are generally hard.
This game contained many minor bugs. The pigs shots occasionally became non lethal, but that could be worked around by restarting level. Ducks were immortal in some places so you had to learn when they could be hit, but that could be worked around since they had a predetermined pattern. Sound occasionally disappeared, but that could be worked around by restarting the game as it saves the progress.
Despite the many bugs I decided to give this game maximum score because the bugs could be easily worked around and the game was very fun!