Bostonianish person here: it hasn't changed Boston. My brother-in-law was running the Marathon that day, he finished about 30 minutes before the explosions.
Watertown residents' cars are no longer universally decorated with "W Strong" stickers. The feds had to strain mightily at the jury pool to get jurors willing to consider the death penalty -- sentiment in Massachusetts was 2:1 in favor of having Tsarnaev rot in prison.
Insofar as the Tsarnaevs had a political goal, I don't think they achieved it.
The Boston maraton bombing cost a fuck ton to clean up and deal with too - many thousand times as much as the enemy used (what 100 dollars worth of cooking ware?).
I don't consider it a particularly sophisticated attack, but it was undeniably effective both at injuring people and at spreading FUD.
Aircraft are an attractive target if you can cause the aircraft to crash, but most terrorist attacks on aircraft don't have that result.