Not the case.
'Once' is not the typical musical; while the char actors occasionally sing, they sing for good reasons, ie. they're alone, they're performing, or (spoiler) they're recording.
The movie takes place in Dublin, where a poor Irish street musician meets a young Czech immigrant. Basically they develop a friendship, but previous relationships stop them from dating, even though they're falling in love.
That's as far as I'll go with the plot, since anymore would spoil it.
The tag line of the movie is "How often do you meet the right person?" with the movie's title, 'Once', written underneath. I don't think that needs any more explanation.
The underlying message of the movie asks the question of what we, people in the modern day, do when confronted with love. If it doesn't work with our plans, if it isn't convenient, will we still follow it? Or is true love only true love when it's convenient?
Can we possibly miss our true love because we were too busy to notice?
Because it's an Irish movie, there are few, if no Hollywood clichés. One of the things I absolutely loved about the film was the names of the two main characters. They're never spoken throughout the film, and listed in the credits as 'Guy' and 'Girl'.
I watched this movie with three of my friends originally, not paying attention. A couple days later I decided to watch it by myself late one night, and it brought me to tears. Now, I will note that it isn't a feat of any movie to make me cry, I'm kind of a pussy in that respect, but I honestly connected emotionally with both of the main characters.
If anyone is looking for a powerful modern film without the typical Hollywood makeover, I recommend 'Once'. This movie pertains to anybody who is caught up within their responsibilities and their view of what 'should' be.
So basically, all of us.
As I said before, my favourite song of all time is 'Falling Slowly'. In one of the first scenes of the movie, Guy and Girl sing this song with only a guitar and a piano and it is the most powerful scene in the movie. Naturally, I had goosebumps when I watched this with my friends, but the other three stopped what they were doing to watch, and they commented on their goosebumps. It full on deserved the Oscar it won for Best Song.
"You have suffered enough
And warred with yourself,
It's time that you won."