1. Does the 2" pipe have a p-trap in the slab?
2. Using a flashlight, can you see the water level after pouring some water down it? Would have been nice if it had been boxed in instead to allow for any adjustments, but removing the concrete and replumbing it will not be too difficult if at all necessary.
3. Do you have any specs or pictures of the pipe layout (with vents!)? I don't see any vent pipes in your picture; would be ideal if you had photos of the pre-pour pipe layout too.