This type of oxidation does not usually have any major problems, as long as it is not laccase associated with botrytis, that's a separate discussion. Some things can be done to prevent the oxidation at the crush/juice stage, but by the time we get it it's too late. Some wineries prefer to add sulfite and crush and press in inert gas blanketed equipment, which does prevent the enzyme activity, but leaves the must susceptible to rapid oxidation if this special handling is not maintained throughout. Allowing oxygen contact of the must without so2 allows the oxidation of some components which gives the brown color, but at the same time the enzyme is deactivated therefore leaving the must more stable to further oxidation. There is some loss of polyphenols, but take your pick, high levels of bound so2 or some loss of polyphenols. Higher levels of so2 used pre fermentation cause an increase in the so2 binding once fermentation is complete; i.e. you'll need a higher first dose of so2 post fermentation to achieve your desired free ppm. Ascorbic acid can be used in addition to so2, it helps, but be warned, if oxygen exposure is not limited, once the ascorbic acid is spent the oxidation and browning will be faster than without ascorbic acid. Ascorbic acid is best used when the must and wine are protected with inert gas.
I'm not an authority on the subject, but I have made a couple of batches (Riesling, Gewürztraminer) that had some enzymatic browning and they turned out fine, once the fermentation was complete, the brown particulate dropped out and the wine was clear. As far as I could tell the flavor was good, in fact very good, but unfortunately I didn't have anything for comparison.