I have had the opportunity to weigh between the quality of a bricks and mortar University and the Open University as I have attended both doing Computing, software development and software engineering related courses.
I started studying with the OU in 2002 due to personal circumstances not allowing me to pay for conventional Uni tuition so I opted to work and study with the OU as I am aiming for a BEng Hons degree with them.
As I was made redundant and had enough cash to go to Uni, I applied through UCAS and got places so I had a choice between Uni's.I studied a BSc Computing Hons degree to which I am about to graduate with. By the way, I started at the 2nd level as I got OU credit transferred and not the first as other unis wanted me to start on the 1st level.
The teaching quality of the OU was way better and the level of the materials taught was higher than was taught at 3rd year. I took a gap year to gain some experience and I was made redundant (recession). With no opportunities I studied with the OU again whilst in my gap year and was very well prepared for my final year which I got a 1st for a particular module.
In a nutshell, the exams and assessments with the OU is far harder (but do prepare you well) than the University I went to and teaching quality and materials is the best I have seen. The advantage that the brick and mortar Universities give you is that they "spoon feed" you the material and encourage you to come to lectures to make face to face contact with lecturers. The tutorials from the brick uni was not that good as the OU. The good thing about brick unis is that you get a degree in 3 years rather than 6 or 9 years which is what it would take normally.
I have 545 credits accumulated between both universities and each has its advantages and disadvantages which each person has to look into his/her own light. It is a crusade if you want to go through the path of the OU and one which you will have to consider carefully as it has many challenges.
In answering the question if the OU has a low rep, the answer is simply no! The people who think that the OU has a low rep are misinformed or simply haven't tried a course. The OU is much harder than regular unis. Tutors from the brick uni were OU tutors themselves as part timers and they also teach full time in their Uni and each tutor tells me that the OU is very hard.
If you really think the OU has a low rep, then by all means enrol to a course, finish it together with a full time job and then tell me what you think!