very 同 very much 既問題

其實very和very much沒多大的分別，只是very much比very所表達的情感更強烈。

另外，very和very much 是形容詞(adjective)，而disappointed也同樣是形容詞(adjective)。

不過，我們大多數會用very來形容disappointed 這類詞語，而very much，我們大多數都不會用在disappointed 這類詞語，而通常都是只會用在規定的英文字詞組合，如：Thank you very much.

I very hate you! Wrong!
I hate you very much! Right!
This is very tasty! Right!
This is tasty very much! Wrong!
至於disappointed嘅問題，下面嗰句應該只係話佢非常之咁失望，所以要特別加個much嚟強調！

He was very happy 和 He was very delighted一樣解。那麼因為 happy是 adjective，delighted 也可看作 adjective了。由此類推，disappointed也是 adjective了。
Very 是副詞。根據定義，副詞可 modify 形容詞或另一副詞的。
你的第一例子：very 是 modify一個形容詞…disappointed了。
而第二個例子是與副詞 much同用，那是 modify另一副詞了。而 he was much disappointed和 he was very disappointed以及he was very much disappointed，也沒有很大的分別呢！

2009-01-27 18:37:20 補充：
Very much 已成為習慣性用語，是連用的了。這是因為 thank you very much.的說法吧。
He is very much thanked by all.是說得通的。但 he is very thanked by all 或 he is much thanked by all.都沒聽過。前者簡直沒有想過；後者想來會是通順的吧！