I think it depends on the context -
and what the person is trying to accomplish.
Is the person aiming at a purple ribbon at the State Fair?
Is the person just learning how to put two pieces of fabric together for the first time?
Is the person mentally and physically able?
It's always a good thing to start out with something positive - but if the person truly wants to improve, then I think suggestions for how to do that are appropriate.
If the person is just looking for compliments - then I go for the "as honest as I can be without hurting the person's feelings" - which can be quite an exercise at times!