I went from a 2011 2IS 350 F Sport to a 2014 3IS 350 F Sport. There are a few things that I liked about the 2IS that I wish they included in the 3IS:
the plastic covering in the engine bay. I liked the clean, very well finished look...
The scuff plates that were single piece looked to be better finished off rather than the rubber seal separating it into two pieces...
I liked that the rear of the front seats in the 2IS were finished off nicer rather than being able to see the 2 zips on either side of the seat backs in the 3IS...
Of course, the LED interior lighting (being such a new car the 3IS should have much more LED lighting technology in it!)...
I miss the flip out door pockets that were finished in a nicer feeling plastic rather than just moulded/blown plastic as per the 3IS.
The 3IS is a far superior vehicle and I wouldn't have my 2IS back any day. Sure, there's some things where I think they've gone cheap with, but everything else far outweighs those points! The 3IS makes the 2IS look and feel very dated, especially the interior.
2IS interior is definitely dated now compared to 3IS, but I do miss some items from 2IS including sunglasses holder, ventilated seats, illuminated door sills, LED lights in footwell and LED lights in center console storage box.
Things they failed on the 3is: cooling seats, lack of storage(coin holder/sunglass holder),working infotainment system, cup holder placement. Stock stereo is lackluster at best.
Why these shortcomings are worth it: driveability! It's exciting to drive it(2is was very dull), styling ( is very unique from anything on the road, 2is looks dated now). Seats are awesome (comfortable and supportive. I also prefer nuluxe to leather now. Everything is rock solid, not a rattle in the place.
06 IS350 to 14 IS350, huge change better in almost everyway especially interior, handling, and the updated tech. Lack of memory and ventilated seats bothered some, kinda stinks that it wasnt in the 14 model but that may change for 15. I drove the 06 again after a few weeks in the 14, and you can definitely tell the difference in the transmission, seat comfort, and seat height. It feels like it sits a lot higher. Bigger backseat is a plus too
15 Mustang GT Premium, Performance Pack, Navi
14 IS350 Nebula Gray/Rioja Red + FSport + ML/Nav + JoeZ Intake/Exhaust
06 IS350 Crystal White/Black + Sport/ML + 2014 IS F Sport Wheels
I am also debating if this is worthing now. I have a 2010 IS250 and I could get 19-20k for it and not sure if the updates worth $17-18k extra. Ift would have been a different story if they'd update the engine.
I went from a 2009 250 to a '14 350 f sport. Inside and out, it is night and day. Do I miss the buttery soft leather? Yes. But that's it. The new car is so much more fun to drive and just looks great inside and out. Only gripe is the lack of interior ambient lighting.