Yeah likewise I've been enjoying it also. Me thinks that I'm going to be a bit tired for the next few weeks at work.
Can't wait until they get in the mountains as the Giro has some serious climbs.
On my front I finally got the chance today to take my bike out with new groupset for a decent-ish ride today of about 65km.
Initial impressions are very positive, a quick break down.
Shifters: Suit my hands much better as they are thinner, the adjustment screw which changes the distance between the brake lever and bars is great, much more refined than just the shims that are available on the 105 gear. I wound them in most of the way for my short hands and reaching the levers for braking and shifting both from the drops and on top of the shifters is a cinch.
Gear Changing: Both front and rear derailluers do a great job here. The 105 was good anyway but the Ultegra is just that little bit smoother and quicker. The front is the biggest improvement over the 105 and it's very swift and smooth, totally fuss free. I tested it a couple of times by not backing off on the pedals at all and it didn't care, swapped chainrings in both directions without a hitch.
Crankset: Turns the chain as it should

, nice and quiet, looks good in my book and not that it really matters to me but it's a fair bit lighter than the outgoing one.
Brakes: Holy smoke Batman, these are the biggest improvement over the previous group by far. The stopping power is immense but much more modulated. The older gear where a bit like an on/off switch which required a fair bit of finesse. These ones you can grab hard and they pull up up very quick or a gentle touch just washes of a little speed. I didn't test the front to max but with the rear I did and the power is there to lock the wheel at any speed. What's nice though the lock doesn't happen as quick as the 105 did, just so much more modulation in-between. Really I can't speak highly enough of the brakes.
Overall I couldn't be happier with the new group and have absolutely zero regrets about purchasing it.
Many happy km's in front of me to come.