Basically, this is the same as the Nは A(い)-い／A(な)です construction. Here,V dic.こと is used in place of N. The i-adjectives and na-adjectives used in this construction are such words as むずかしい(difficult), たのしい(enjoyable), おもしろい(interesting), つまらない(boring), and たいへんだ(troublesome), which involve the speaker's judgment.
コンピュータを 使う ことは むずかしいです。
It is difficult to use computers.
ながい 文を 暗記する ことは たいへんです。
It is hard to memorize long sentences.
