The Challenges make you really pay attention to a song's construction and add an extra level of challenge, both for high-end and intermediate players. You find yourself suddenly acutely aware of your note streak and your playing technique. Instead of trying to make it through a very difficult song, you can go back and attempt a Challenge on an easier one instead and still feel like you're achieving something. It adds breadth and variety to the solo gameplay; I wouldn't have thought there were this many ways to play a plastic guitar. Guitar Hero has always excelled on top-end difficulty, and this adds an extra layer for players who want more challenge without disadvantaging those who don't.
The actual gameplay differences between Rock Band and Guitar Hero are quite subtle, and only really relevant in the upper echelons of play. On Hard and Expert it becomes clear that Rock Band likes you to memorise simpler patterns and perform them flawlessly, whereas Guitar Hero prefers to have you barely managing your way through brain-melting note charts. The hit window for hammer-ons and pull-offs is more generous, the charts dance around the screen more. On Rock Band you can 98 per cent a song and still not achieve five stars because you broke your streak somewhere in the middle; Guitar Hero rewards you for your prowess more than your consistency, pushing the scoring balance more towards hit percentage than streak length.
Which one you prefer comes purely down to personal taste. Unless you just don't like Guitar Hero's way of doing things (and if you're any kind of rhythm-action player, you'll know by now) there is absolutely nothing to criticise about the note charts. Songs are transformed wondrously into challenging levels whose note patterns always, always feel like a true representation of what the music is doing. There's never a moment of disconnect, no awkward or artificially difficult sections that remind you that you're playing a plastic guitar. Neversoft is mastery of its tools is complete.
The song selection itself, for me, strikes the right balance between long-overdue, well-known guitar classics (Smells Like Teen Spirit, Plug In Baby, Sympathy for the Devil), songs I'd never heard before in my life but quickly grew to enjoy (Streamline Woman, Young Funk), unexpected personal favourites (Du Hast, A-Punk, Wannabe in LA) and comic relief (Play That Funky Music, Hungry Like the Wolf). All of them are great fun for drummers and guitarists, but there are inevitably a few that most vocalists won't go anywhere near, and bass still isn't quite as accomplished as it could be.
It's a shame that all the songs have to be radio versions, too - "(blank) the unborn in the wooooomb!" growl Iron Maiden in 2 Minutes to Midnight, the Gorillaz' line about ass-cracks in Feel Good Inc is left unfinished, poor little Blink-182 can't even get "drunk" with their best friends in Rock Show - but otherwise they are, as is now expected, completely intact. Even all 13 minutes and 40 seconds of live Peter Frampton.
It's a relief that Activision hasn't seen fit to release a whole new set of instruments with Guitar Hero 5, letting us use the ones we already have instead, but on other compatibility issues the publisher has been less than generous. World Tour DLC is compatible with Guitar Hero 5, which is only to be expected, but only 35 of World Tour's on-disc songs work with the sequel, and you have to pay a premium to download them. It's not really acceptable, and is the only touch of cynicism evident in the game.
The four things that give Guitar Hero 5 a considerable edge over its competitors are the flexible, challenging difficulty, peerless customisation, music creation tools and, above all, frictionless, sans-menu multiplayer. As far as song selection goes, it's a matter of personal taste, but the sheer breadth of Guitar Hero 5's offering means that there has to be something you like. If anything, excessive breadth is the track list's weakness - there are bound to be so many songs you haven't heard of that familiarising yourself with them is a bit of a mountain to climb.
It would be terribly fashionable to be able to moan about how Guitar Hero is running itself into the ground whilst Activision counts its money, but there wouldn't be a scrap of truth in it. There's just nothing wrong with Guitar Hero 5: no horrible new art direction or gimmicky new features (3's guitar battles still haven't quite been forgiven), no backwards moves, no ill-advised changes to a winning formula. And yet, Neversoft has refused to let the series go stale, broadening the multiplayer and single-player options to give you more game for your money. Indeed, the developer is only creating problems for itself: how can Guitar Hero possibly get any better?
9 / 10