Both this set of controls and the Dura Ace that preceded them offer some significant design improvements that can only put a smile on your face.
First off is the new design of the internals. Shimano has moved the guts of the lever out of the body of the unit and into the lever. This allowed them to open up the entire bottom which makes keeping these clean much easier. In years past, when STI levers would fail it was not uncommon to be caused by grit and dirt buildup in the body of the lever. Now with the open design, that grit falls right out (and let's say you have a penchant for racing in the mud in the fall- you can use a dry spray lube like Boeshield T9 and hose these things out; keeping the insides clean and in excellent working condition has never been easier).
The second advantage to the new guts is that they have moved the brake cable routing and brought the Servo-Wave technology from their mountain bike brakes to the road. There is a knuckle that now pushes up on the cable in the lever through the lever stroke which  increases the leverage of the initial pull, and  allows for greater modulation at the end of the throw. Pair this with Shimano's incredibly stiff brake calipers and you suddenly have a significant increase in brake strength and control, with a smoother, lighter action.
One last feature i have to point out is the new lever reach adjustment. In the past, women (in particular- but anybody really) with smaller hands had 2 choices on the road- either suck it up and reach, or use a shim in the lever to bring it closer to the bar. The shim was less than elegant and not entirely easy to come by. With these new controls you have an adjustment bolt built in so everyone can tailor the lever throw and reach to their own preference.
The one change here that i'm luke warm on is the new cable routing which takes the housing back along the handlebar (as Campy has done for years). This is great for aesthetics, for cable longevity and for mounting bags, lights etc up front (for touring or rando for example). But there is one group who lost on this: cyclocross. While the controls themselves are easier maintained and cleaned which benefits CX, with the new cable routing you can't make quick shift or brake cable changes for example if your housing gets stuffed with mud from the pre-ride before a race. Also weekly cable changes during CX season (which isn't uncommon in the PNW), means you now likely have to change your bar tape weekly as well... which adds $20+ and another 10 minutes to the job.
All around there are some serious improvements to the already great Shimano road line. It's obvious Shimano isn't in the marketing game- they are in the engineering game. That means their products are consciously designed, well built, and reliable. It also means the 'cool new products' from other companies who put their dollars into marketing instead of engineering look great in an ad, but will not provide you with the years of hassle free service that Shimano will.