On Skill Deconstruction: 4th Edition Dungeons and Dragons
There are mathematical issues with the way skill challenges presented. If you have to roll an 8 or higher, it's always to your advantage to avoid being part of the challenge. There's one section where Kieth Baker comments that it isn't broken because of his house-rules to 4e. He has several bizarre comments in that story like it's supposed to be broken for first level characters because first level characters suck. These problems were ones of math, and eventually were fixed to the point where the Skill Challenges were mathematically playable.
The reason the skill challenges were a problem is that they are binary success or failure. Your party rolls a number of times to and the only thing that matters is hitting that success threshold. When you succeed or fail you stop rolling. So that creates a situation where the only concern is rolling the good skill against the easy challenge, regardless of the actual situation in the game. Attempting to engage in the challenge in a way that is not optimal contributes to the entire party failing. Some excellent cogent discussion is here. Some numerical analysis on the earlier broken mechanics is here. The Alexandrian talks about a lot of the problems with the math and design here near the bottom of the page. Note that these aren't problems, but analysis of the math showing in what ways it does the exact opposite of it's intended goals. Here is a list of skill challenge articles about how to make them function.
Personally, as I've stated, tossing dice in turn around the table to get something done on a pass/fail basis is a waste of time.
But there are good things about the 4e skill system itself. Like that it has one?
4e has a skill system! Let's talk about it.
Ignoring skill challenges, 4e does do some things to try and address problems.
1) Everyone increases at skills that they use and don't use due to the 1/2 level bonus. This addresses the problem of the high level character who can't meet a skill check along with the rest of the party.
2) The skills are condensed and focused towards the combat tactical game. This means that in areas where you are not in combat it plays a lot more like old school play.
3) You do not have to spend a long time picking skills. You can just select whichever ones you are trained in, check them off and go.
It's a DC 20 Nature check to know that bears attack with their claws) these improvements are in the spirit of moving in the correct direction.
They are good! I like them!