Personally when I take melatonin, I fall asleep quickly but I get weird dreams and I feel my sleep quality isn't the same. I took it for a little while (a couple of months) and now only take it when I'm really struggling to fall asleep.
I've tried it a couple times. I have to allow extra time to sleep and have someone there to wake me up since I sleep even heavier than normal - more chance to miss the alarm, unfortunately. I wake up groggy, but once that passes I'm very, very well-rested. Also, I get weird dreams as well.
I decided long ago I wouldn't try it again without a doctor's advice, which is probably a good thing since now I live in Norway and it is only available with prescription. Some folks do wind up needing it if they take it every night, though. I worked in a pharmacy in the states and heard the pharmacists' advice on this very thing many times.