I do not regret claiming any of them. I am preparing to take the MCAT this summer and used AP credit for intro bio, chemistry, and physics (~half of the test concepts) and do not feel very disadvantaged. In class, I will sometimes have trouble with a concept or miss a question on a test and one of my friends will tell me that they learned it in their intro course. However, these tend to be minor points and the total effect is small. That said, I should qualify my opinion by letting you know that I studied relatively hard in high school, knew the material well, and got 5's on all of my tests. That's why I emphasized that you should be very comfortable with the material before you claim credit for a class that serves as a prerequisite. Prerequisites are required for a reason and the minimum accepted AP score isn't necessarily a good indicator of competence.
As a mechanical engineer, I don't know if a good physics background will be critical but a strong background in calculus is definitely necessary.
While you should be careful about claiming credit for courses pertinent to your major (e.g. physics and calculus), you should have little worry about claiming credit for core requirements like government, English, history, arts, etc. Just get those out of the way and forget about them.
For the random high school student looking to get core classes out of the way: If you have the room, try to take AP Art History or AP Art. A lot of incoming students do not realize that a Visual & Performing Arts (VAPA) credit is as required as government and English.
Last edited by frever; 06-10-2012 at 07:52 PM.