There isn't really one source that you could get all the information from so I'll just list all the good sources of information..
1. GMATClub - There are several forums in GC where you can get a sense of the the "character" of a school and great information on the strengths and relative weaknesses of schools. Look into the Business School Reviews
forum in particular. There are some really excellent posts in there.
2. Businessweek - Take a look at the MBA Profiles for various schools in the "Rankings and Profiles" section. They give a very nice snapshot of all schools, including comments from current students, that I found very helpful.
3. Poets & Quants - Another good site that does a lot of school comparisons (Booth vs. Kellogg, HBS vs. Wharton etc.) and has interviews from Deans of various schools.
4. Current students & alumni - If you can get in touch with any acquaintance / friend who is a current student or alumni, then this can prove to be a huge treasure trove!! Don't underestimate the wealth of knowledge that you can glean from alumni and current students. They've been there and done that and if you know them well, they wont BS you..
5. School Guides from Admissions Consultants - Most admission consultants prepare school specific guides. These are not free. I haven't had a chance to really go thru those so I can't really comment on how helpful they are..
Once you have shortlisted some schools, then depending on your location and other constraints, you should also try to visit schools or at the very least attend information sessions or informal coffee chats that the schools may conduct in your city. You will eventually develop a good 'feel' about the culture of the school after a good deal of research and that will in turn enable you to analyze your "fit" with the school..
Hope this answers your question! Good luck!