Oooh thats a tough call.
Driving straight down the island through the city would be a 15km route, whereas the new road would be a 50km trip all the way round the outside, but, when the island is totally gridlocked at rush hour, it would probably be faster (especially if you're going to be using Salam street).
At quieter times, it wouldnt save you any time and would use a lot more petrol, and if you were doing it in a taxi, the driver would be whinging all the way. I guess probably not, most of the time.