Ran across this yesterday.
At first I didn't know what I thought about it. It is not the usual thing. While the arrangement is very true to Gershwin's, the singers' style is different from the operatic style one is accustomed to. Smooth and bluesy and without a lot of emotional intensity. Also some ornaments that are very nice but again, not what one is used to. Maybe it's a bit jarring to hear the black English constructions like "I is" with a very non-black accent: for instance, "I" having the diphthong that people who talk that way don't put in there. ("Ieee", not what's usually written as "Ah" although that's not exactly right.) And the over-pronounced "r" in "Porgy".
But it's growing on me, definitely.
Here's a very nice, very sweet example of the usual thing, for comparison:
I suppose that the fact that these two very different expressions of this song each work so well shows the versatility and the - structural strength? - of Gershwin's work. Not a musicologist, don't know how to express this really.