My new phone was expensive, but at least it has excellent quality and a long battery life.

at 是介词，表示"在...方面"或"处于某种状态"。 least 是形容词 little 的最高级形式，意思是"最小的、最少的"。 at least 是一个固定短语，表示"至少"，用来强调某个情况的最低限度或积极方面。