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.
Awesome Music: Be it some thumping techno, murderous metal or dizzy dance music, you'll surely find something for you. You choose the music it plays. Awesome Music is an assured part of the game.
Game Breaker: Super Bombs in the original. At point blank range, it decimates bosses in a single blast, usually giving you plenty of time to rack up Dare Devil bonuses gradually if nothing is around until the next wave of enemies show up.
The Steam version of Classic and Ultra. Sure Windows users do have to pay for relatively cheap add-ons for file support that the Macintosh users don't have to pay for, but beyond that they have access to internet radio for music, (optional) social feeds through RSS and Twitter, other possible configuration tweaks. In the case of Beat Hazard Classic on PC and Mac on Steam, it also has access toBeat Hazard Ultra's Suicidal difficulty if it's unlocked in the expansion pack.
The retail PC release by THQ has most of the same content as the original Xbox LIVE Indie Games version with some added songs and the addition of the Suicidal difficulty, which might be good for those who prefer the original.
That One Boss: The Hydra-like boss from the Ultra DLC is this sometimes. It has the ability to curl up into a ball and repel ALL attacks, and can stay like this for any amount of time. This boss can also un-curl, fire, and re-curl in less than a second. Combine this with the fact that they have a large amount of HP and, once they do this for while, there's a bunch of other enemies and/or bosses on-screen, and it becomes very frustrating. On the other hand, it only curls up when you're too close to it. Stay away, and you're (relatively) fine.
Scrappy Mechanic: The PC streaming function of the original Beat Hazard for the Xbox 360. If your music takes too long for the game load, it will immediately terminate your game; other times the game will play an entirely different track from the one you wanted. The Xbox 360 version of Ultra is even worse as it flat out fails to scan any music stored on your computer.