Impromptu?? Hard to imagine how that went down. Was it piano and vox, live...then the orchestra added? Or was the music complete before the gal just tossed the vocal on, non-challant-like??
Anyway, it's good work. I assumed he want a critique. And what it has to have is dynamics, to drive a passionate vocal performance, and make it interesting and pleasing for its length.
Here's my fave after a quick search for a
great version. Note the swell, fold, thinning and thickening in the orchestration, and the dynamics of the vocal, in accordance with the conductor's interpretation. And add the organic timing, too. The version posted is metronomic.
https://www.youtube.com/watch?v=Z9nrtFkj6Bo&feature=related