Apologia is a very rigorous college prep series. I don't usually recommend specific curriculum, because I know it's all about "fit" more than a textbook. When it comes to science, though, I had such success with the curriculum we used, that I really do recommend it - even to my clients that are not Christian.
I know it for a fact that Apologia is a great college preparation because Alex (my non-scientist son) was able to pass a CLEP in Biology 3 years after taking Apologia Biology at home. He earned a 4.0 in Engineering Physics in college after taking Apologia Physics. Remember, he is NOT my science major. I made him take that engineering physics at community college with his brother, because he was too young to take a class by himself. So he learned well from the books even though he didn't "love" science. Apologia is GREAT stuff.
I know for a fact that Apologia is great college preparation because my son Kevin is an electrical engineering major in college. He still refers to his Apologia Physics book now and then. He used Apologia Chemistry over the summer, to review for a class he was taking. He has reviewed his physics book frequently. It's been one of my "best buys" for curriculum, because they have literally used them for 5 years. Kevin has a fabulous GPA in engineering, and I believe it is in part because he was so well prepared with Apologia Biology, Chemistry, and Physics.
If you want to make Apologia even MORE rigorous, it is possible. You can go through a book in a semester instead of a year, and make it an AP course if you want, but it's not necessary at all, just an option. I have heard of some "college prep" AP classes that actually take a child 5 hours a day to complete. That would be so frustrating to spend 5 hours a day on one class! One mother was letting core subjects in reading, writing and math slide, just so her child could get an AP Chemistry credit. That's a lot of work for not a lot of benefit. It's easier to keep your subjects at the level of your children when they do it at home with a homeschool curriculum.
Apologia is a self-teaching homeschool curriculum, so kids can learn it on their own, and moms don't have to know what they are doing in order to be successful. That's a big deal, because I didn't have a clue about physics, and barely was able to keep up with the chemistry.
Yes, absolutely Apologia is college prep. It's not perfect, because no curriculum is perfect. All textbooks have typos- ALL of them - and I'm sure someone could find a flaw in these books like you can find a flaw in every book. Still it's great preparation, and I recommend it even for my clients that aren't Christian.
Lee Binz, The HomeScholar