The attacks on ambition are many and come from various angles; its public defenders are few and unimpressive, where they are not extremely unattractive.  

【翻译】对野心的抨击之辞非常之多，而且来自不同的角度；公开为之辩护的却寥寥无几、效果平淡无奇，尽管他们并非一点也不起眼。

【分析】where 在这里表示“让步”，意为“虽然，尽管，然而，但是”。等于whereas，though。