He isn't a great PM, but he is far from the worst. We have to be realistic, he came into government when the public purse was in a horrid state and at a time when there is just so much mess everywhere that you can't blame him if he has to make some difficult decisions.
Worst ones, hmmmmm I can't decide who but in recent times it would go to Gordon Brown aka the credit card man who thought there was no more boom and bust, except the country was going through one of the biggest booms (fueled by a housing bubble on debt) and then one of the worst ever bust. Not to mention his record as Chancellor wasn't particularly stellar either, selling off much of UK's gold reserves at rock bottom and worst yet he even announced in advance when he would do it......stupid ****ing ****ing idiot.
John Major wasn't fantastic either.....the idiot that started massaging unemployment figures by moving the unemployed to be on Incapacity Benefit. This was the idiot that shouldn't have been PM especially considering how good his predecessor was.
Other useless pricks that became PM :-
Wilson and Callaghan, the bloody fools that ran Britain into the ground to the point of requiring an IMF bailout.
Edward Heath, hopeless idiot that did nothing and instead came up with stupid policies like the 3 day work week.
Eden & McMillan wasn't particularly great either especially on how they handled the Suez crisis and lost hold of much of the colonies in Asia.
Atlee, for all the talk about him and the NHS, there wasn't really much else to shout about him.
Chamberlin, a pre-war Gordon Brown, weak and lacked what it took to be PM.
Lloyd George, nothing special about him and he could have done better with regard to Treaty of Versailles.