YES, doom desire will still work if Jirachi is knocked out, as the effect is on the defending pokemon. it will not, however, continue working if the defending pokemon goes to the bench (and maybe evolves, not sure on that one).
i used this at the prerelease to great outcome, but i do not see it fare so well in modified play. its first attack is great: get a card you want for your next turn, for free. and if your opponent's big pokemon is not going anywhere next turn, discarding two metal energy is great for a knockout.
7/10