Helsinki is nice for a young student who just wants to have fun and go restaurants and pubs with friends. Hipsters can rejoice here. When you grow older it becomes shitty if you are still forced to live in a concrete box and can't afford a nice house.
Areas vary a lot, avoid the ones with more foreigners (greener areas on picture) and junkies, and you're fine.
I moved here during corona, it is quite cozy but at the same time I haven't yet seen its potential when everything has been locked down and nobody goes anywhere.
It's also a very small city, so not too crowded at all.