Good:
Superman The Movie - a classic. Great score, great tone, good performances, nice effecs for the time.
Okay:
Man of Steel - weighed down by too much exposition and a codex subplot that goes nowhere. Could use some more color. Great action sequences.
Bad:
Superman II+The Richard Donner Cut - Most people remember it more fondly than I do. A lot of the new humor doesn't connect and it sorely misses John Williams. Both versions are worse than the original in every facet.
Terrible:
Superman III - a step down in every imaginable way from the first two
Superman IV: The Quest for Peace - gone completely off the rails
Supergirl - aggressively terrible
Superman Returns - zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz