This pattern indicates that the degree or quantity of something surpasses a certain reference point, which is often a stated amount, a noun, or an action. It is commonly used to compare reality with expectations, such as 'more than I thought' or 'more than necessary'. With a noun like 予想 (expectation), 予想以上に means 'beyond expectations'. With a verb like 思う (to think), 思った以上に means 'more than I thought'. This pattern is quite common in both speaking and writing, but it is not overly casual, so it works in most contexts. It is important to note that 以上に is typically used with adjectives and verbs that describe degree, such as 大きい, 難しい, かかる, etc., or with verbs that indicate change. The main clause often contains an adjective or a verb that is intensified.