Even though SK+ is sold as a J product on some other outlets (on UA and Lifemiles it is considered J for award redemption), it is in reality Y+. The lounge access and refundable/changeable ticket are nice features offering flexibility and when the fare is not that different from regular Y, then it is a good value.
Comfortwise I hated not having a blocked middle seat. This is one area where SK could make SK+ fares more attractive.
The crew was smiling and did their job efficiently.
Flight arrived a few minutes late, not a major delay by any means.