It's a good uni and, as rarely found in the online universities spectrum, a highly reputable one. I've met several OU alumni in the past who were professional and bright lads.
I did one diploma course that I meant to articulate to a higher qualification as they have that kind of articulation that allows you to take things steps at a time rather than jumping on a full degree. Never did complete it because i had other things happening at the same time. but will definitely be jumping back into it once everything else settles.
the way the programmes are run, well at least mine, were fit for purpose but of course there is a need to do own reading, a lot of this actually.