Reports are, it tasted lousy, due to nearly zero fat content. Additionally, "real" beef has flavor overtones resultant from the feed the animal was raised on. Thus, corn-fed beef tastes different from grass-fed beef, even if both cows came from the same cows.
I don't expect vat-raised hamburger, much less steak, being commercially available anytime soon. . . . . simply because if it doesn't TASTE good and have the "mouth feel" of genuine beef, you're not going to get enough buyers to make it a commercial success. . .
Lets say you have 100 cows of the same breed, and you have 5 fields, each with a different type of grass. Lets say you put 20 cows in each field and allow for 2-3 years to pass. What would be the end result, as far as taste goes? Each field - unique diet input - is going to create a unique taste in the meat. You can eat a steak from a cow from each field, and if your taste sense is sharp enough, you will be able to tell a subtle difference between each of the fields.
The Matrix - the environment - is VERY important, in a number of subtle ways. I would guess that epigenetics and mRNA play a role in all of this. Each field/grass is going to provide different mRNA to the cows, which will have subtle effects on the way their meat develops. A lab and a natural field are going to provide different Epigenetic Signals (inputs), so we should naturally expect to see different outputs.
This link explains this concept a bit further: Affects of mRNA.
The first time I read about this concept, I was instantly reminded of this Jesus quote, from the Gospel of Thomas: (7) Jesus said, "Blessed is the lion which becomes man when consumed by man; and cursed is the man whom the lion consumes, and the lion becomes man."