Oooh! Not what I expect to see in a challenge such as this. You MUST have had a tripod I would guess, but on the other hand the walking couple is barely blurred so it wasn't too long of an exposure. Either way, it's an eye-catching entry, definitetly meeting the challange IMO. Good luck!
i think the subjects are a little lost in the tones that are used. i also think the city scape could be framed a little better, you have St Pauls, cut out and nothing on the right of the shot!maybe just have another look at the set up to see if an extra adjustment might make the killer shot
i really don't like to comment on borders but i'd like to have seen this with a beige one that doesn't grab so much attention. your smoothing of the noise has left the details a bit too fuzzy. i have trouble connecting with your characters.
A nice shot though it's a slight strain to make out the people against the bright city lights (and yes, my monitor is calibrated). I still like the shot though.