There's been a TON of progress, actually. You have to keep in mind, that this area is an entire city block.
1/8 of a mile by 1/8th of a mile.
It took like 3 years just to haul away the main debris.
perspective is everything.
This is a model of the proposed freedom tower.
lower manhattan island is over 2 miles wide where the WTC is located
an old map, but with a scale on it.
And, there has been some progress made on the freedom tower already. Its a good 10 stories from the looks of it. You can find more details here:
Home | Freedom Tower - 1WTC - One World Trade Center - New York City - a community project based on Ground Zero's rebuilding
Plus, the foundation is below sea level. Unlike uptown, there's limited bedrock to lag bolt these skyscrappers into. mid town has none, which is why there are much shorter building sin mid town (i don't think anything over 40-ish stories around times square)
you can see how the skyline of Manhattan is basically a "U". downtown is top, uptown is lower part of pic (looking south)
And since this was damaged with the fall of the WTC, the re-enforcements to hold the pressure of the entire atlantic ocean needs to be re-built
not a small engineering task by any means.