Investment in human resources.

Investment in human resources.

GMC offers outstanding customer service. They pride themselves in servicing all Buicks and GMCs with quality parts and and a fine service department.

No, "outstanding" is not a linking verb. It functions as an adjective describing the quality of something. Linking verbs connect the subject of a sentence to a subject complement that renames or describes it.

Quality is an extremely subjective term when applied to art. Quality in drama, though is usually is decided by the audience. It's the standard though that will apply to the quality. If the acting, scenery, and etiquette are good during the performance then you have high to outstanding quality.