Technicals: I highly suggest you learn to use channel mixer for converting to B&W (if you use photoshop). You have a lot more control. To my eye the picture looks just a tad too sharp in places. The subject, unfortunately, is also lost in the BG. I know you were somewhat going for this, but you have to do it so the viewer understands the trike has been abandoned, but it actually stands out on a technical POV. Selective desat might be one application.
The feel: As mentioned in technicals, I think a limiting factor is the trike is too lost in the composition. Some of the textures, like the grass, are too harsh as well. This is a shot using some gaussian blur might even work better.
The game: Maybe even go for sepia? That might have added to the nostalgic feel and gotten you another tenth.
I kind of like your shot, but it seems overly processed to me. Although it does look better on my mac monitor than my pc at work - so bumping it up one point.