I find a substantial difference between the two cabins, no matter how short the flight.

In business class, which BA call "Club Europe":

* the table between the two passengers seats is a handy place to store your drinks, books and papers
* the cabin is calmer and feels much more spacious - you do not have to compete with a neighbour for arm space
* the food and drink is good and comes quickly - in my experience it is easy to get as much to drink as you like.

All in all Club Europe provides an excellent flying experience. I recently took a return trip to Istanbul, which is one of the longest Club Europe sectors. I had a great and comfortable flight.

The different standards between the two cabins might be compared to Standard and First Class on the trains. If you find an upgrade to First on the trains worthwhile, then you would most likely find the same upgrade on the plane worthwhile.