The sneak was NOT a good play call. It did looked planned and I thought it was extremely foolish.
Denver risked losing the game by doing what they did. That play ONLY would have been OK if they had a timeout. I'm not saying the play didn't have a chance or anything like that, but if you don't have a timeout in that situation, you don't do that.
The first down meant nothing, it isn't college football where the clock stops. It was TD or nothing which is why that play call was wrong. I do think they went for the win. I think they thought they'd catch them but throwing a 3 step pass to 6 foot 5 Brandan Marshall is also going for the win and there's not the risk of them stopping you short of the goaline like they did.
They had to run out and kick the field goal with 1 or 2 seconds on the clock, that was absolutely unnecessary and if that kick would have been blocked or shanked, you'd be reading threads this morning about him being fired, I'm not kidding.

If they make the first down, then they can spike the ball to stop the clock and kick the FG.
It was a GREAT call, but had the worst outcome:
Best outcome = catch the D napping and get the TD
2nd best outcome = get stopped short of the GL, but get the 1st down. Spike the ball, maybe try a throw into the endzone, kick the FG.
Worst outcome = what happened. They couldn't spike the ball to stop the clock since it was 4th down.
Could they (DEN) have asked for a measurement? Wouldn't that have given them some time to get the kicking team on the field a bit quicker?