Why is it in Passé Composé when expressing emotions and not Imparfait

Question

Why is it that " et j'ai vraiment apprécié l'espace supplémentaire" not in imparfait if they are describing the setting and expressing emotions. The next time they express their past emotions it is in imparfait "et nous n'étions pas fatigués à l'arrivée."

Accepted Answer

J'ai vraiment apprécié l'espace supplémentaire. -- I really appreciated the extra space.
Using the passé composé, the speaker views this as a single event. If the sentence were in imperfect tense, it would sound like this to French ears:
J'appréciais vraiment l'espace supplémentaire. -- I was really appreciative of / I used to appreciate the extra space.
It implies some kind of continuation like: 
I was really appreciating the extra space when someone knocked on the door.As a child, I was really appreciating? I used to appreciate the extra space in my room.Two years ago I appreciated the extra space -- now I don't anymore.