Fenix 3 absolutely looks good, and imho in the area of design it outstands Ambit 3 atm. I have them side by side (as you have seen on the earlier pictures) and A3 Peak looks a bit like a plastic toy watch compared to F3.
The other positives on Garmin side (imho again) are:
+The display is sharper, better looking and a bit larger (the colours being an added value, and the black background is more 'black' then in A3... where it is 'brownish' black)
+The phone integration is waaay better then in A3.. for example you can read a whole sms message on screen!! shocking!! (hello Sunnto guys.. it can be done!), integrates with the calendar (you can see your tasks on screen..current day), can control music play on your phone (no use for me, but it can be done), shows weather reports (not perfectly located yet but ...) and ... listen to this... it works with Android phones!! (hello again Suunto..btw I use iPhone)
+ Map screen.. well they took away the basemap functionality from F3 (which sucks) but at least it can show you your activity runned/hiked/biked path on screen (imho mapping/navigating features in A3 plainly suck..I promise not to call Suunto guys again)
+Connect IQ is great, you can customize your watch much,much further then Suunto ever allowed (tbh here you need much greater programing skill in C division to do so or you have to wait for someone else to do it for you)
+WiFi .. sync and upgrade..great ! ... but the watch has problems with finding networks atm
+Ability to upload your activity to many sport services.. this part of Suunto policy just makes me go mad.. but to cut things short.. you don't like Garmin Connect, fine, upload your activity directly to other services and just don't use it.. but if you don't like Movescount.. well... you got a problem

+Ability to configure the watch in the watch.. no need for phone/PC/Mac.. and now you can backup your configuration data which was a drawback of F2 (just a 'bit' more complicated then it should be, as if they couldn't add a backup/restore option). This is one of the drawbacks of A3 as during the Christmas Movescount outage you not only couldn't sync your activities but also you couldn't configure your watch (beyond the basic settings if you owned an iPhone).
+Again imho F3 is more comfortable to wear, lighter and better fit (not with the steel bracelet though which is pretty heavy)
+All the other little things (like daily steps count or sleep tracking) which are there but I wouldn't miss them it they were not
So in my opinion Fenix 3 outstands Ambit 3 in almost every way... except one (which I think, unfortunately for Garmin, is most important) - GPS accuracy (also altimeter accuracy as was pointed out to me)
I am not ready for a final opinion, as I didn't have much time lately to test F3 on certified tracks, but I think atm that Fenix 3 is less reliable GPS wise then Ambit 3.
They did remove the problems with 'spiking' on the track (which original Fenix and Fenix 2 had) but the 'smoothing' algorithm seems to cut too much of the track and generally the outcome is shorter then the real distance. Ambit 3 is not perfect here also, it tends to cut corners but still it comes very close (50m max) on 10k course... this is acceptable. Now on Fenix 3 I got the error around 150m-200m which is not good at all. Especially areas with worsened reception (high buildings, forest) are where the problems show.
The other thing I forgot about earlier is altimeter accuracy... something wrong here as well, it shows for example that I have moved around 10-50 m vertically during sleep, Ambit's solution to use internal accelerometer to check if we are changing works much better. Hope again it is a software glitch and can be fixed.
I will wait and see see if Garmin can fix the GPS and altimeter accuracy by firmware updates... if they do Fenix 3 would be a great choice and I will stick with it.. if they don't I think I will not trust them again and I will stick to my Ambit3 until Ambit4 arrives, so atm I am keeping both watches as I just can't decide which one to ditch ;-)