It was a real eye-opener.

Meaning

The experience was surprising and revealing.

Examples

• John: 'Visiting that country changed my perspective.'
• Alice: 'Sounds like <b>it was a real eye-opener</b>.'
• John: 'Definitely, <b>it was a real eye-opener</b>.'
• Alice: 'The documentary showed a side of the issue I'd never considered.'