I agree with 'promising'. I cannot comment on 'ready' as I have not reviewed his patches much. My impression is that he has a talent for noticing glitches in the details of existing behavior and docs.
"He is often doesn't noticed many details in first versions of his patches."
If he has trouble being as critical of his own work, he would not be the first. It is a needed skill, though.
Has anyone communicated with him, perhaps privately, on how to improve his patches, so he learns by doing it himself? (I know very well that editing and commiting is often more expeditious if one wants the patch committed *now*.) Mentoring, if he wants it, could start now rather than after granting commit rights.