"It's easier said than done."
Instead of the literal translation, there is also the chengyu 成語 that matches the same meaning: 談何容易
Um, I know some people may translate this into Chinese as 談何容易. But 談何容易 is not a 成語 (just Classical Chinese), nor does it mean exactly "easier said than done", but closer to "how can you say that is easy".
Though 何 means how, it can mean what. I don't only literally translate statement; I also deeply consider how each of the characters are posed.
Regardless of how the statement is translated, the idiom is in fact 成語. Here is the site.
It's not only in classical Chinese "era"; idioms also appear in literature, movies and newspaper articles. Many authors are being very articulate with such statements. You will see how some meanings of the terms, like the one I mentioned here, are not included in the translation.
It can also help to watch movies and shows in both Chinese and English subtitles to learn how the translator interprets the meanings accordingly.
The both of you are right: it is a lesser known 成语 (as I myself discovered through the link above) and it is more commonly used as a sort of exclamation. In fact, or because of that, many people know both meanings but wouldn't know that it is also a 成语.
Can anyone offer some insight in the difference between 作 and 做 which both seem to mean to do?