1. What a pity / shame!

太可惜了！

2. I expected it to be much better.

我原本指望会比这个结果好。

3. What a bummer!

真糟糕！

4. What a let-down!

真让人失望！

5. All my effort went down the drain.

我所有的努力都白费了。

6. I was so looking forward to..

我原来还一直盼望……

7. I messed up.

我搞砸了。

8. That’s (just) so disappointing!

真让人失望！