The whole 1.x to 2.0 stretch was a rough ride. I had to maintain software without From 2 to 3 was pretty OK since very little changed in the language only API'

The whole 1.x to 2.0 stretch was a rough ride. I had to maintain software without From 2 to 3 was pretty OK since very little changed in the language only API's got updated. From 3 to 4 mainly adds stuff and doesn't break much.