As so often, Christopher Hitchens gets to the heart of things:

When Tony Blair took office, Slobodan Milošević was cleansing and
raping the republics of the former Yugoslavia. Mullah Omar was lending
Osama bin Laden the hinterland of a failed and rogue state. Charles
Taylor of Liberia was leading a hand-lopping militia of enslaved
children across the frontier of Sierra Leone, threatening a
blood-diamond version of Rwanda in West Africa. And the wealth and
people of Iraq were the abused private property of Saddam Hussein and
his crime family. Today, all of these Caligula figures are at least out
of power, and at the best either dead or on trial. How can anybody with
a sense of history not grant Blair some portion of credit for this?