Call something good, call it cool, call it nice, call it excellent, but if you think it is really outstanding, call it a humdinger! Humdinger is a word for a person or thing that is remarkably excellent.
Be careful: calling you grandpa's fancy new car "a real humdinger" may make you sound like you're older than he is. Humdinger's got a newsboys-at-the-baseball-game, dawn-of-the-20th-century feel to it. Maybe that's because the word was coined in the 1880s as a combination of hummer and dinger, two words for people or things that are big, strong, powerful, or just awesome. By the early 1900s, humdingers were everywhere, at least according to the salesmen, college boys, and other slang-slingers whose penchant for exaggerated boosterism made humdinger what it is today.