Well, the sun shone, the sights of the city were breathtaking, the crowds were - almost nonexistent, actually. Or pretty indifferent, except for a few pockets around the major landmarks.
You'll have to excuse any typos, I'm posting this at Zurich airport on my way home and this swiss keyboard has the keys in all the wrong places.
Set off confidently expecting to finish around the 4 hour mark, and was bang on target until about 23 km - but with a cloudless sky the soaring temperature meant I ended up just slogging along hoping to finish. Came in about 4:14, having picked up the 4:15 pace group with 5km to go and amazing myself by managing to produce a respectable run over the last 5k.
The course was fairly twisty and turny around the middle of Rome, and there's certainly plenty to look at, but then heads out of the city next to a fairly busy road - so lots of exhaust fumes to breathe, just what you want. You also pass the finish when there's still 10k to go, which is a bit demoralizing.
Strangest moment - meeting a couple of guys from school who I haven't seen in about 18 years (they finished well ahead of me as well).
Worst moment - really thinking I was going to have to abandon at 32k
Best moments - finishing (thank god), running past the vatican, enthusiastic support at the Trevi fountain and the spanish steps - much needed by that stage.
So, almost exactly the same time as Paris last year, although a much harder race and feel like I ran much more strongly - sub 4 later in the year maybe??