Israel is now holding nothing back against Gaza--its tanks and infantry have entered the strip with the public intent of capturing Hamas rocket launching sites (and likely very large weapons caches nearby) and dismantling them. The Israelis are also likely sending in large numbers of special operations forces to try and take down as much Hamas leadership-in-hiding as possible.
There's little to say yet on the operation, except that it shows a real commitment for Israel to pay the necessary political costs to take down Hamas in a way that would allow Fatah to take control of Gaza if/when it wins elections that Abbas is calling. Strangely, it may be this very war that enables the Israelis and the Palestinians to make peace. A reminder is due that Hamas does not recognize Israel's right to exist--it is only interested in driving Israel out of the area, and that it took over Gaza strip in a civil war in 2006 after losing elections to Fatah--their continued presence has been a tough roadblock for the Israelis, and it seems the Israelis feel they finally have the political capital with their neighbors to finish Hamas off. And despite all the criticism coming Israel's way, it looks like they're right. But now the fate of this operation depends on the military's ability to achieve its objectives without "mission creep" or a quagmire.