I have recently purchased the St. Pat's Collection. So far I have been enjoying it quite a lot. Pieces are rather easy, but still sound good. The version of "Danny Boy" included in this collection is easier than a different version I happen to own, but the new version sounds every bit as good.
This collection would be ideal for a self-directed adult who plays for casual enjoyment. One can master these pieces in minutes -- most of us would not want to make this sort of occasional music into a major project.