Questions & Answers about El concierto fue genial.
Spanish often uses the preterite (fue) for a completed event seen as a whole.
A concert is a finished event, so El concierto fue genial sounds very natural: you are giving an overall judgment about it.
Era is the imperfect, which is more often used for:
- background description
- repeated situations
- ongoing states in the past
So:
- El concierto fue genial = The concert was great.
(a complete past event)
Using era here would usually sound less natural unless you are describing it in a different kind of context.