Actually, I'd say the site is mostly fine but its target audience are kayak beginners with no prior kayak/kayak building knowledge.
The site may introduce those people to basic concepts and give them brief overview of the sport and the technique. In this sense this site is similar to information posted on about.com site. Children might be another group that finds this site useful.
On the other hand this forum is the other end of the spectrum - a lot of people here are deeply involved in the sport and would not learn much from buildkayak.com
I agree that other peoples material should be used with permission. I also think some of the commercial promos are a bit over the top and intermingled too much with other material (a'la 'Wired' magazine)

: I want to be considerate here, but there isn't much useful info on your site.
: The explanations don't make sense and are so abbreviated as to be useless.
: Also, I note that you're using other people's photos - for instance, I see
: you've borrowed some of Tom Yost's Sea Bee photos - are those used with
: permission? Why not just provide a link to his site, which is clear and
: well done and a recognized resource - no need to reinvent the wheel, after
: all. Sorry to be blunt, but you did ask for opinions, after all.