These are the Skype Forum numbers.
As of today there are 92528 articles, written by 32221 registerd users. There havae been 19007 topics created.

Now the numbers are all on the main forum page. Of the 92528 posts there was 32205 or 35% that were posted to the general support forum. For the topic SkypeOut there are 8682 posts for 1702 topics. Thus SkypeOut accounts for 9.4% of the posts and 8.9% of the topics created.

So what's it all mean?
Actual participation (more may have visited, learned but not signed in) in the Skype Forum is less than 0.11%. That is one hundredth of a percent on 29million registered users. Now many of these "events" are positive, or suggestions etc.

In the forums there are also "SuperUsers" who delight in helping out those with questions. Some have thousands of posts to their names. I don't know how many posts the superusers have. It must be about 1 in three. Which means if you make a post it gets answered.

Now SkypeOut. SkypeOut now has one million users. It has 1702 topics. let's assume that these are all separate cases, and mega complaints. If that's the case then SkypeOut complaints are running at 0.17%. Many of those complaints are about "buying" problems. While some interconnect issues have been blogged and well entered into the forums this number suggests that consumers "understand" the trade-off.

So what's the number?
1 or 2 in 1000 may have had a problems with Skype. Problems can stem from PC's, quality of the connection, even understanding how to put in the right number (I had a call like that this am).

When you are adding 155000 users per day that means 225 people per day may have some problems. Given what I know about Windows, installing a Vonage account, dealing with Comcast or numerous other new products this looks like a very low number to me. It will always be too much. If you look at the new Skype help section they are trying to address this too.