Some value added: here's my experience with the program to get this thread truly started.
I think that Columbia is a fantastic school for some things, and that you can really take advantage of what they have to offer as a postbac. I came in knowing the Columbia system, since I had been an MPH student who'd taken classes on the main campus, which I think really helped.
Columbia is rather no-frills when it comes to their postbac program. It's really a cash-cow for them, and they treat it as such. You will have an advisor, but it's up to you to really make them notice you (so that they can write you a great letter) and the advice that they give you will range from moderately useful to downright wrong. It's super expensive, and many people (at least 30-40%, I would say based on my totally unscientific estimate) drop out of the program.
I loved most of the profs, but when you start in Spring, the curve will likely be higher b/c you're off sequence, and the teachers will not necessarily be as high quality. You'll also have to make it through a year with Dr. Mowshowitz, the infamous Biology professor. Bio will not be a 'gut' with her, and it may be the hardest class that you take...possibly ever in life? I loved the class, but it won't pad your GPA like it could at other institutions. The program isn't the most collaborative environment...it can be, and I felt like I had enough people to depend on, but the program doesn't really help to foster a supportive environment. But, I felt very prepared for the MCAT at the end of the program. I decided not to even take a prep course, and just self-study, and it turned out very well.
At the end of the day, I think you want a postbac where you can 1) get a stellar GPA, 2) be super prepared for the MCAT, 3) get good guidance and support for your application, 4) at a decently reputable place, 5) at the lowest possible cost (time and money). Columbia does OK on 1 and 2 if you're a stellar student, generally poorly on 3, wonderful on 4, and very poorly on 5. So, I wouldn't NOT recommend it (haha), but I would seriously consider other programs that might offer more of these criteria. If I had to choose again, I would probably look into Goucher or Bryn Mawr or Hunter. And, I feel like I'm WAY more positive about the program than many of my friends.