Just bought a bottle of El Dorado 15 year. ED 12 might be my very favorite rum, so I was shaking with anticipation when I poured some ED 15.
I have found that I am often regretting posting a first impression, but with that caveat, I have to say I much prefer the 12 to the 15. Probably because my fondness for sweetness seems to outweigh my appreciation for complexity, but that's my first impression.
Considering my local liquor store has ED 12 for $24.95 and the ED 15 is $33.95 the ED 12 is an unparalleled value (at least to me).
ED15 reminds me a lot of Flor de Cana 7, another rum that I enjoy from time to time as a sipper even though it lacks the sweetness of my preferred sippers. Quite a price differential there too