You will get an EAD, however the MOMENT you use it, you will invalidate your H1b status. This is a problem, because you have to fulfill the 3 years of your waiver requirement IN H1b status.
So, you can file the I485 along with the I140, but you cannot use any of the secondary benefits that come with it. The main advantage is that your spouse can file an I485 as well and CAN use the EAD.