The Declaration of Independence is actually full of specific criticisms against King George. Indeed the bulk of the document is made up of 18 sets of grievances, each beginning with the words "He (meaning, of course, the king) has" For example, the first of these grievances claims that the king has failed to approve legislation passed by the colonial assemblies:
He has refused his Assent to laws, the most wholesome and necessary for the public good.
Placing the blame at the feet of the king, instead of his ministers or Parliament, was a rhetorical strategy that highlighted the tyrannical (according to the revolutionaries) behavior of the British government. In reality, for example, the colonial laws, mostly dealing with the issuance of paper currency, that failed to gain royal assent had, strictly speaking, been overturned by either the Board of Trade or the Privy Council, not the king himself.
But some sections of the Declaration, indeed about a quarter of Jefferson's draft, were omitted by Congress. The most famous was the following passage condemning the slave trade and laying the blame for it at the feet of the king. This was apparently deleted by the Congress due to objections raised by South Carolina and Georgia. Most of the other deletions made by Congress involved issues of diction and economy of phrase. As historian Pauline Maier has pointed out, there were other phrases that did not pass muster perhaps because Jefferson had simply "gone further than he had to" in his attempt to demonstrate that the monarch was in fact a tyrant. For example, Jefferson concluded the grievances section with the following statement:
Future ages will scarce believe that the hardiness of one man, adventured within the short compass of twelve years only, to build a foundation, so broad and undisguised for tyranny over a people fostered & fixed in principles of freedom.
This passage was deemed unnecessary, perhaps even redundant in the context of the rest of the document, and was removed. But overall, the tone of the document is that of specific and emotional grievances against the King George.
Source: Pauline Maier, American Scripture: Making the Declaration of Independence (New York: Vintage Books, 1998) 137-150.