I'll have to defer to someone else on comparing it to AP classes since I have no experience with them.
Think of it like this: a year-long AP class goes through about 1 college semester of material, which is normally 18 weeks (I'm running off memory, so I might be off on that). A summer course is usually 6 or 8 weeks, so the pace can be quick. Now, obviously it won't be as rigorous as an AP course, but it isn't something to jump into your first term without thinking it through. If you can find easy profs on
RateMyProfessors.com , then that's an entirely different story.