Like Sidot, I too have just passed the 1000 mile mark with my 1.3 manual in red. We traded in a Scenic & an Aygo for the Jazz, hoping for the versatility of the former and the economy of the latter: so far, it's living up to those expectations. I think Honda have done a pretty good job, but like many other things in life nothing's perfect. I like the analogy of the new girlfriend picking her nose !
Economy: this depends so much on your style of driving and your route, but for comparison with Sidot's figure I'm averaging (according to the on-board computer) around 50 mpg for my normal commute (around 12 miles each way, mixed town & country). I've just done a 300 mile round-trip on motorways and the computer was showing 61.3 mpg at the half-way point and 59.5 when I got home, so I'm pretty pleased with that.
General comfort is comparable to the Scenic - although the Jazz is notably noisier inside at motorway speeds - and better than the Aygo,. Rear seat passengers are almost universally impressed by the amount of space back there.
Windscreen glare: personally I haven't noticed that, but then we haven't had a lot of bright sunshine in the last month !
The various electronic assistance aids take a bit of getting used to (eg exactly when you can expect the Idle-Stop system to work), others have commented on the auto lights, and having to explain the various beeps and alarms to your passengers, etc. The thing that has the potential to turn from a minor into a major annoyance is the infotainment system. Yes, it has DAB and various other bells & whistles, but the touch-screen is distractingly insensitive, the settings are hard to find, it doesn't have the versatility promised in the brochure, and I seem to have an intermittent fault that causes it to stop without warning.
But having blagged a £1700 discount on the price (sorry folks, that's a special scheme available through my work and not available to the general public) I'm broadly pleased with the overall package. Let's hope Honda's famous reliability keeps it all working.