Is '做得较出色‘ good Chinese?
Seems to me that it means that something is outstanding, remarkable, or it is not, in which case it is commonplace. I suppose this begs the question 'Where does remarkable begin?'
(Someone)做(something)做得较出色 is perfect Chinese. 较出色 can be translated into relatively outstanding
I think Chinese tend to be modest when compliment someone related to them. So it is common to hear the boss praises his subordinate 做得较出色 or a mother praises her son 做得较出色 in front of a third party.
It is perfectly fine if you remove the "较" which as user3306356 pointed out "It's more formal (较 vs. 比较). 较 means relatively or comparatively".
P.S. if you hear 较出色, someone/something probably is pretty outstanding.
较出色 is a somewhat formal expression, which is mostly seen in official or semiofficial documents. It literally means "relatively outstanding". That is to say: it is not of the top tier, but a bit better than expectation. If it is used in a student's grade report, I think it roughly corresponds to A- or B+.