For starters, I apologize for the quality of the photo - the bed is so large and my sons' room so small that I had to splice together 4 different pictures to get a picture of the entire thing. Now, onto the project!
I found the details lacking in the instructions quite often. I definitely recommend having sketch-up installed on your computer so that you can turn the pieces around and see them from both sides - in many parts you're layering wood and attaching pieces on different sides. So being able to rotate the pieces in sketch-up was a huge must for us.
It took myself and my girlfriend about a week or so of working several hours a day to finish this up. Since most of the bed is made in sets of 2, the second set always went faster than the first, since we knew what we were doing.
I also found we needed different size materials than the instructions suggested. 1 1/2" screws were just long enough that they came out of the other side if they were countersunk at all, so we ended up switching to 1 1/4". The plans call for 32 3" bolts and 4 2 1/2", but we needed 32 2 1/2" and 4 2" - when we first put it together we had 1/2 of bolt hanging out of all of the holes - obviously not ideal for 3 little boys running around.
All told this project cost us somewhere between $250 and $300. I had to run out for new 2" screws at least twice, so make sure you buy a lot. We got lucky with the paint and found this super bright yellow/orange in the oops bin for $7, and decided to do a wash instead of painting so we could still see the wood grain. (And my 8 year old promptly took a marker and wrote each boys' initials on their beds - kids!).
All-in-all I'm incredibly happy with the bed - it fits the exact need we had, and unlike the only other plan I found online for a set of 3, it doesn't attach to the wall (which is important as we rent) and will be fairly easy to disassemble when we move.