There's a lot more use for money in this game...unfortunately, it is also much harder to amass this time around! You get very little out of training, and only the tournament races (which don't seem to give you any cash) are repeatable, despite the larger store stock and costly eggs.
Training all these ducks also feels much slower than past games. The way the skills are spread out by area that you must win tournaments to progress through rather than being available as training normally is also rather strange, and detracts from the party-style of duck raising a bit.
Both of the starter hairstyles in the first area give a different hairstyle when bought.
Not a bad game, but a bit of a grind at times. There's no denying that 3 and 4 made definite improvements in some ways, particularly with pretty graphics and trying new things, but overall I think the first two games are probably a bit more fun. This is actually the first game in the series I got tired enough of playing that I didn't finish in one sitting, and not just because it's a little longer.