I have taken 2 Sun exams so far. I found the SCJP exam pretty difficult but the SCWCD was a bit easier. I've decided to go for the SCBCD exam, probably the latest version(5). How difficult are both exams compared to SCJP and SCWCD?
I didn't take SCBCD 5.0, but I took the old one and most other Sun Java certifications.
Some old certifications have been too easy, and obviously they want to change that with all the new versions: SCJP 1.4 is easier than SCJP 5.0, SCWCD 1.3 was considered very easy, but SCWCD 1.4 is not, SCBCD 1.3 was very easy, but my impression from reports is that SCBCD 5.0 is hard. (SCJP 1.2 was considered hard as well.)
My sources are mock exams, several real exams I took myself and the score reports from JavaRanch. You will find many 90+ and even 100 % results in the ones I called "easy", and many failures in the ones I called "hard". I do not have concrete statistics.
One of the reasons why the new ones are hard is the new "performance based" question style which naturally is a little more ambiguous.