I am very fine with content which is achieveable by less than 1% of wow community, nice to have something like gladiator in pve.
Challenge modes are the fastest way to obtain valor points, they will be great for hardcore players who need valor for item upgrades in 5.1, lets say its mogushan palace daily challenge, you form your group and run it in 12 mins for gold (85 VP) then hand in daily (80 VP)... 165 valor in 12 mins is pretty damn good
Truth is it takes time to practise them abit, its not like you go there and do silver+ on the first run, you have to progress through them the first time, get to know what to do at certain points. I'm member of semi hardcore raiding guild with 3/9 dungeons on silver so far, didnt have much time to do more than this, but there's no rush and for me personaly its one of the best features in MoP, from what I've played so far i must say it's just great, its much different than raids and much much different than the heroic versions, you need organized group, you need tactic, you need cc, finaly i got to use all my char's abilities in pve.
Ofc many people gonna flame challenge modes, saying its no new content, saying gold is not doable by 99.9% of wow community (which is actually best thing about it), but thats the same people who flame dailies, saying they are grindy and most people cant do all of them because its so time consuming, so what? Why most people got a feeling they have to stay on par with hardcore players, that they should get all the gear more easily, that they should be able to do all the dailies every day, that they should get higher arena rating easily, that they should be able to get all gold in challenge modes?
"You are a pro or you are a noob, that's life."