I like the nice, unforced atmosphere in this photo. It looks so peaceful, careless and relaxed atmosphere, taken directly from their lives. No glamour, pure life as is. That makes the photo very strong.
In a way the holga effects (vignetting, focus and tonal range) play a mixed role. It can be perceived with a mismatch in the atmosphere, but also be seen as a tool to emphasise the feel. Not really sure, it has an "easy going" feel about it I rather like. That also fits with the snapshot like composition. All very subtle.