The reason given for launching the attack, an imminent Iranian threat, is beginning to sound melodramatic. The US wanted a plausible excuse to assassinate this guy.
If we get a hot war with Iran, was it worth it? Nope.
If we get numerous assymetrical attacks on American and western assets, was it worth it? Hmmm. Arguable.
If Iran decides to change its policies and become peaceable, was it worth it? Spits out cornflakes. It ain't going to happen.
Best possible outcome. An arguable benefit, that Iran realises there are costs to its behaviour, won at the expense of probably many lives and the loss of the US rules of the road re state-run assassinations. Putin can now say, well, America does it, so why shouldn't we?