They have a very good track record of building skyscrapers quickly, competently, and with environmental conservation in mind. I think it was their recent 30 story building that is rated to withstand level 9 earthquakes. That said, building a 30, 50, or even 60 story building is totally different than building a 220 story supertall. If they actually can assemble a 220 story building in 6 months (or whatever their new time frame is), I will be blown away. It will probably take AT LEAST that long just to create the foundation, which I understand is not counted as part of the build time.
The CEO of the Broad Group is a bit eccentric. Check out his house and the company's headquarters:
I am not a huge fan of this project, but I hope it will succeed. The Shanghai Tower is much more beautiful and fits into an impressive skyline. It's only about half built and is already considered a supertall.
e: wtf, they've changed their projections from 6 months to 3?? I don't believe this is possible, even with a modular design. You might be able to build at that rate up to 50 or 60 stories, but beyond that constructions slows dramatically. This will be a monumental achievement if they are successful.