I'm of two minds with the Skill challenges. On one hand, I like that they tried to put something in game that wasn't just "beat you with a stick"
On the other, a good deal of the skill challenges seem more "roleplay" oriented.
If you want your adventure to go on, you are going to let the players "succeed" in their challenge one way or the other.
I think a good example of skill use was seen in the DnD Day game. There were puzzles present. They players could have A. figured out the puzzle just by being good at puzzles. B. Gotten lucky C. made relevant skill checks to get puzzle hints, or D. upon being "beaten" by the puzzle, allowed entry due to circumstance, (in this case, a hobgoblin opening the secret door to grab a smoke)
I think I'd allow RP to completely substitute die rolls.
"I'm searching the room...I roll a 27" is fine, and keeps the game moving.
"I run my hands along the wall slowly, looking for a slight shift in the stones...I take off my helmet and undo my ponytail to help notice any air currents by the hair blowing in my face..." etc.
Its all preference...and the skills are there for a reason, so use them, but I'd much rather hear a character's well thought out (or well improvised) speech then just base things off a die roll. (though if the character doesn't have the proper skills or decent charisma, I might not let him try, unless he roleplays his terrible score

)