The answer must be yes and no.
At a micro level, in killing and injuring, a degree of chaos caused in a relatively small area of the city, yes. In disrupting parliament in London and Edinburgh yes. In making the police all jittery as whether there were to be parallel attacks, yes.
At the mid level, getting in Parliament and killing a few well known or celeb people, Government ministers, MPs, prominent journos, abject failure.
At the macro level, in disrupting the UK and getting them to cease drone attacks and the rest on ISIS, abject failure.
Motivation to get other Muslim extreme prats to come forward and have a go, the jury is out. What seems apparent is that the major staged event like 9-11 or London 7-7, seems to have gone for the moment, as our security services are cracking these, a switch to the low-tech/individual strike like yesterday, in Brussels, Orly or Nice. Expect more of these.