The label of an open university will affect you in the hunt for corporate juggernauts, or furthering your studies in prestigious universities, especially overseas.
However, within Malaysia, the term of an open university is not yet known widely, but I do advice you to consider alternative options yet before pursuing for open universities. I heard the quality of education is not bad, but it's the goal behind this credential.
Do you want to further your studies overseas? Or do you just want to work in Malaysia right after this credential? Or more as a collection of qualification to strengthen your position in your current occupation?