I transferred from a traditional university to the OU, as I was having problems with depression/anxiety. I have to say I was impressed with the support they gave me - e.g the mentor I received was actually helpful. The learning material itself seemed as good, if not better, than the material from my previous university. I've done two courses with them so far - "Starting with Psychology", which is an introductory course, and "Biological Psychology", which is a level 2 course. I will be starting a level 3 course next month (Infectious Diseases), as I was able to transfer credits from my previous university.
The degree I'm studying towards is Life Science, which is the degree closest to the one I was doing at a traditional university.
I received DSA (Disabled Student's Allowance), which pays for a study support mentor, who helps me get organised and not stressed out, etc. You can also gt extra time on exams, special equipment, etc. I was able to get this type of support from the traditional university as well, but it seemed generally less supportive.
The other good thing is that the OU base financial support on your own income, and not your parents like traditional universities. This meant I was able to get my courses paid for me. A lot of people doing the OU work full-time and study part-time, but I am doing both part-time, as I think I'd get stressed out otherwise.
http://www.open.ac.uk/