A lot of it has to do with what you want out of the deal. Everyone is entitled to their own opinion, of course, and clearly they are expressing it to you, but at the end of the day you and your partner have to dance together, not these other coaches, or other people. The positive qualities you mention are quite positive indeed, are far more outweigh the negative ones you provide. Besides, those negative qualities will disappear the longer your partner dances; especially if he is a hard worker.
To me, hard work triumphs each and every time over almost everything else.
The one thing I will say is what others have also voiced: six months is not nearly a long enough tenure to tell anything in a partnership. Perhaps others will disagree, but I remember watching a lecture in which the lecturer (and I cannot recall who so I will not drop names for fear of being wrong) said, and I am paraphrasing, that no one stays together long enough in ballroom to truly achieve anything; almost everyone breaks apart too soon, and then find a new partner and there is still a period of adjustment for both persons. It takes a few years to get a feel for one another as partners and as dancers, and to get somewhere consistently on the competition circuit.
It takes no effort to destroy what is being created.... your partner sounds like a decent partner. It sounds like a conversation with him, and a coach you trust implicitly, is in order. As well as a reflection session for you to figure out what you want out of your own dance career. Perhaps a new partner is in order if your goals and desires differ. But if you guys are driven by a shared and mutual desired outcome, then a little more hard work is all that you might need.