Good luck guys, my little brother is taking them right now. I can't imagine how crazy it must be to study for them given how my friends in high school would complain about them for weeks. Agreed, if you're going to a university straight out of high school then its worth to take them. Personally I preferred the community college route where you essentially got paid to go to school assuming you signed up for financial aide because the tuition was so cheap, picked off super easy A's and then transferred (at Wharton its pretty easy to transfer from there to UH).
Seriously. The one thing I regretted in high school. Dual credit was pretty much a blow off, with the college credit WITHOUT having to pay to claim it at UT. In essence it's the equivalent to AP credit here at UT so there's really no point in busting your ass for the same credit. Also just got done with my freshman year, last final today. Just FYI, these last few weeks I have been studying more than all of my years of grade school put together. It's tough man.
This year: AP Chemistry, Spanish, Calculus BC, English Literature, US Government and Politics, Macroeconomics At my school, AP is weighted a lot more heavily on GPA than dual credit. Also, AP credit is good almost anywhere, whereas dual credit does not transfer out of Texas.