The level design was uninspired and uninteresting. It was very flat in most places. So yeah, the level design was pretty much horrible.
The subweapon leveling up was a nice concept, but executed very poorly. The level goals were way too high.
The art, while "good" in its own style, was overly cartoony and a large stray from the Castlevania tone. It cheapened the atmosphere.
The characters were goofy for the most part. The heroes were just a silly pair of kids, dancing through a magic castle. The most 'serious' moments were usually failures at being serious.
PoR gets an A for weapon variety though. Whips! And not only that, diagonal whipping! So long overdue in my opinion. I wish they went the whole mile with it and gave us diagonal swording, and down whipping too.
I also liked having two character available, like DoS's Julius mode. Thought the team activities were completely under used. I wished there was more of that.
It was nice to get a leveling, and always running, Richter mode too. However they did an epic fail by using loli Maria when the adult one would have been far more interesting.