Her style was clear but lively, informative but not preachy, and for most readers truly exhilarating.

【翻译】她的风格清晰而活泼，内容丰富但不说教，对大多数读者来说确实令人耳目一新。

but 是转折并列连词，没错。语言的精髓在于“简练”。重复累赘的词语是语言表达的大忌。任何语言都有“承前省略”现象。例如，本句如果不省略的话，就会是这个样子：

Her style was clear but it was lively, her style was informative but it was not preachy, and for most readers her style was truly exhilarating.

红色部分即是省略的成分。