This is a good idea for the challenge. It seems there may be too much light, especially on the pictures to the right. It might also be better with a few less photos, but that's the only thing I can come up with. Nice work!
I'm not sure if this is slightly oversharpened or slighty overexposed. The pictures seem a little too bright, and the camera has lost some of its details. It could just need a little more contrast. The choice of sepia ages the image well. Overall it does an ample job of representing nostalgia.
Nice composition. There's a lot going on in this shot yet you've maintained focus. The photo that's standing vertically at the camera's front throws it off a bit, but maybe you intended that? Very good photo.