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.
YMMV: DJ Hero
Breather Level: While the "Good Thang"/"The Big Beat" mix can be a bit tricky, neither of the J. Period Presents mixes are anywhere near as tricky as some of the mixes you'll do to unlock them.
Contested Sequel: It's heavily debated which game has the better soundtrack. The first game primarily focuses on rock and hip-hop from a decent stretch of decades, with a decent mixture of famous, One Hit Wonders, and fairly underground artists. Meanwhile, the second game focuses mainly on modern radio hits with less rock music.
Crack is Cheaper: Hoo boy, was the DLC for this game expensive. $7.99 for a three pack of songs. Granted, it's rather justified, as incorporating unique remixes between two songs is a lot more difficult than simply acquiring the rights to a song and charting it as in Guitar Hero.
Even Better Sequel: While the soundtrack of which game is better is heavily debated (see Contested Sequel above), there's no doubt that the second game's improved gameplay mechanics (with more freestyle sections, more note types, and changes to the Rewind system) make the second game better from a purely gameplay standpoint.
Narm Charm/So Bad, It's Good: DJ Z-Trip's "Juke Box Hero" vs. "DJ Hero" mix is a fine mix, but the lyrics splice away mentions of guitars and rock music for turntables and instrumental hip-hop. It ends up sounding hilarious.
Both games require you to spin the platter backwards to activate Rewind. As you could expect, this is very finicky, and not doing it at the perfect time will almost certainly make you drop your combo.
Both games also require you to turn the effects dial during certain sections to get bonus points, similar to the whammy bar in Guitar Hero. The only problem is that the dial is very weirdly shaped, and the thing will dig into your skin and hurt after doing it for long enough.
For the second game only, held directional scratches are confusing and difficult to perform. Thankfully, they're used fairly sparingly, but until you get them down you'll lose a lot of combos to them.
That One Boss: In Empire Mode from DJ Hero 2, David Guetta's DJ Battle Mix (MSTRKRFT's Bounce Remix). It only has 6 checkpoints and both players have very little advantage, and no matter how you try, David's trigger happy wits will triumph over you in the end (granted since his lightning fast wits will lock you out thus giving you a slim chance of winning). The only hope you have is to beat him to the punch and be flawless, or lose (FYI: draws don't count).
That One Song: Let's put it this way: If any of the mixes you play are made by the Scratch Perverts, chances are you're not gonna clear said mixes with 5 stars in one go, barring the Easy and Medium difficulties. Case in point, Beats and Pieces, "Groundhog" beat juggle, and, god forbid, the "Galvanize" remix. For the latter you'll get a trophy/achievement if you did not manage to 5-Star it on Expert and one if you do manage to pull it off.
Too Good to Last: A breath of life into the stagnant music game genre, cancelled after two games due to poor sales.
Vindicated by History: The series in general, as well as the soundtrack, became better known after the series' cancellation and it's often praised as one of the most overlooked games of the seventh gen.