I didn´t expect this song, but I hoped for it and was one of the few who appreciated it being on GH5 (although I would have been glad about any COB song there). GH is fun to play with your friends. Of course it´s something else than being able to play real guitar, hell it´s just a game!!! I wouldn´t start learning guitar atm because I can´t afford enough time to practise (and I know you need a good amount of time to do so, I learned playing keyboards when I was a kid and if you want to do it right you have to invest time). But if you sometimes want to play along to good music just for fun, GH is okay.
Back to the song: Well DWEDFN maybe won´t turn into their best song ever (I like it very much though) and it´s not that representative for how COB "usually" sounds like, but:
1) THE COB SONG doesn´t exist anyway
2) Their style changed anyways during albums, especially during the last two. Picking an old song would therefore not be a wise choice nowadays if you want to promote their latest album and gain fans for the future
3) I think the riffs and stuff from DWEDFN is fun to listen to and will be even more fun to play along. I think it´s good that they didn´t choose songs like IYF or HCDR with a "less varying" (hard to explain what I mean, hope you get it) melody
4) I could imagine pretty much every song off Blooddrunk to be fun to play on GH, but maybe they chose it because it´s not too "metal", to reach more people, not only Metalheads? (not saying I appreciate that, just a guess)