I have the 2014. I don't think they changed it much.The stock wheels are now Shimano RS 11, not R-500. 105 is now 11 speed, not 10 speed. The frame is the same as 2014. It's a fine bike in all respects. Handles well for an "endurance" frame.
You might want to be more specific on which aspect(s) of the bike you want input on. I think that's what NJAgent was saying.
I am not a pro, semi pro or even a tri-athlete. I am a 200 pound guy who just loves to ride my bike. So what can I tell you that these bike experts cant? I can tell you why I chose the Synapse over the Defy, Domane and the Roubaix.
The Domane 5.2 i really really wanted to like. I damn near had my mind made up that was my bike- until I rode it. I thought it was very smooth ride, but on my test ride- my toes kept scraping the pavement on hills and on turns. I couldn't get the sizing or fit "just right".
As for the Defy- that was simple. The Defy rides very good... but its an ugly looking bike. Where the fork, top tube and down tube meet is really bulky looking... really ugly in my mind. And I didnt like the color options.. but that bulky frame really eliminated it nearly off the bat.
That left the Specialized..The Specialized felt like it fit the best. My ass was instantly comfortable on the seat. However, just like the Specialized Hybrid, the shifting wasnt as crisp for me and there was chain rub. So there is an issue with the pricing: DO I want the better group set and caliper brakes OR the worse grupo and the disc brakes.
That's when I saw the Cannondale Synapse review.. and holy **** the bike looks BAD-ASS. If you like flashy you can get the matte black and flourescent green/yellow color but I went with the matte grey with the graphics and slight red trim lines. The Synapse is by far the best looking of all 4 bikes. AND BONUS, Cannondale has the Ultegra Grupo AND the disc brakes for the right price- I DIDNT have to choose one or the other.
Ultegra is butter smooth instantaneous shifting and the bike felt great. The bike was smooth, felt fast, and was making no noise.
So- I followed expert advice - when all things are equal, go with your favorite color. So I chose the Cannondale Synapse Ultegra Disc and I have been incredibly happy with the bike. It performs magnificently. I have one minor quibble.. on the smaller chain ring the top 2 gears have some chain rub... But otherwise the bike makes no clinks or clunks, its just me and the bike. The tires are also not very good- I recently ordered some Schwalbe tires for better performance and puncture resistance.
Because I am relatively short, there arent many bikes in my size available for test riding. They actually didnt have the Ultegra disc for me to ride in the size 51. I test rode the 105. The 105 drive train was as smooth. I honestly cant tell the difference. I am not a pro test rider or someone with a ton of experience, just a guy who likes to ride a bike. But I couldnt tell the difference in performance.