These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
The Hero 300 music fits the impending-end-of-the-world mood.
Fridge Brilliance: When fighting the Evil Lord in Hero 300, your party actually fits within the rock-paper-scissors aspect of his game mode; Hero is a nimble, Princess is a shooter, and Knight is a brute.
It's Easy, so It Sucks: The initial modes available are all pretty easy once you understand them. Hero 30 gets progressively harder and throws you more curveballs as you continue, but the strategies for Evil Lord 30, Princess 30, and Knight 30 never significantly change.
There's an Xbox 360 port which takes Half Minute Hero, upgrades the graphics to a Paper Mario/Wind Waker like style, and changes the design of the other modes into more of a Hero 30 type but with different methods of attacking.
The PC version, "Super Mega Neo Climax Ultimate Boy", appears to be more of this, including both the new graphics from the XBLA version, and the original, more fleshed out versions of the other modes from the PSP release. The developers even call it the "ultimate version".
However, it's still missing some things, such as the music player, gallery, and the "Another Goddess" quest.