Largely agreeing with what cerro posted, but here is my take regardless:
Mix-match-compatible (for the most part, it's relatively friendly to mix years/levels/components, including SRAM's mountain range if you want to do something unique)
Light weight ; Fast gear changes ; Double-tap shifting. I love it. It's personal preference, however ; Adjustable reach on the levers, for people with small hands. I don't use this function, but know people who do ; Very tunable. It might be a combination of availability, comparatively-low price, lack of 'auspicious reverence' for the brand/heritage, or the nature of people who tend to buy it anyway, but it certainly has the greatest amount of tuning done to the its components compared to other brands ; The exogram crank is ridiculously awesome. Possibly one of the best single components I've ridden in the past decade and all the more valuable when I consider the price it sells for.
I don't like their graphics too much. The newer (2012-present) derailleurs have improved. ; The spider orientation of their Exogram crank isn't the greatest, but then again DA9000 went to their own unique BCD (with justification), Campagnolo has had a strange compact BCD for quite some time with little justification, and the BCDs on both the standard and compact Exograms are still industry standard ; You will get a lot of people who don't ride their bikes (seriously) enough whinging about you riding SRAM.
Pro: To be honest, I prefered 7800 over 7900, but it was largely the same. The looks grew on me, but I eventually stopped riding it. The shifting is typically supreme, as are most Dura-Ace lines. I can't really say for certain that any front derailleur was better than another brand because I've found steel-red, dura-ace and record all pretty much equal when it comes to the most basic of the derailleurs: the front. (However their 9000 is a lot like the 2012+ Yaw in having an improvement in the Front Derailleur category.). 7900 Cranks are pretty awesome for stiffness, not so much for lightness.
Their design is very modern with flashes of metal and coated-metal, a bit 'samurai sword' like, which is nice. While not necessarily any more 'strong' than the carbon competitors, the metal components lend themselves to a feeling of solidity and durability. (However, everything in this world will break at some point in some way)
Dura-Ace also seems to be available everywhere, which is a plus. It's not like SRAM nor Shimano are in the way of scarcity (some might say 'exclusivity') that Campagnolo is, but most places will have Dura-Ace spare parts on the ready.
Cons: Heavy - (ier than Red). Expensive. Didn't see too much tuning going on in the Dura-Ace world.
-set up. Some people (and mechanics) will state unequivocally that Red is finicky to set up. I completely disagree with them and found it no more difficult than any other group, and no more or less necessary to adjust/maintain through use compared to other drivetrains.
-Sound. As for sound, that's a personal decision. Some people really love the Dura-Ace/Shimano silent shifting, some don't. I felt the shifting was slower compared to Red, but 7900 felt just a little bit smoother. Red has a very distinctive 'thunk' to it, which I love. While it is certainly a fast shifter (especially in sprinting), each shift has such a beautiful, very mechanical sound to it. Kind of silly, but last weekend I found myself shifting through gears while slowing up for my ride mates to catch up to me while on a double, just so I can hear that sound.
-More on sound: some have said that older Red cassette was loud. I guess so, but I wouldn't really know. I tuned the old OG1090 cassette and made it really darn quiet, quieter than the Dura-Ace cassettes of my friends. I now run the 2012+ XG1090 cassette and it's even quieter.
|| Other projects in the works.