DC-wise, I take the Errata'd ones and add +5. Even at Level 1, a DC 5 for "Easy" checks is too low.

It seems to work OK so far, though only when the Players get to pick their Skills. I haven't used them against un-optimized skills yet.

Anyhow, Skill Challenges continue to be problematic - though I hear DMG 2 actually has a good guide for using them.