All ways of talking about temperatures require some assumptions. It is not clear e.g. for someone unaccustomed to the American way of talking about temperatures that 70s, means 70 to 79 degrees.

In terms of expressivenss, I find it very expressive to be able to express temperatures below freezing as negative. It is useful as it is when you get typical winter weather, snow, frozen lakes etc. With Fahrenheit, what one associates with Winter starts at a rather arbitrary point on the temperature scale.

With regards to the imperial system. I quite like parts of it. If only the number system was 12-based. It doesn't make sense to have 12 inches in a foot, when the number system you use is 10-based.

One mistake with the metric system is that they did not base it off any other well known and used units. They could have use pound or foot e.g. as basis for defining the Kg or meter.