The single most important factor is also the most subjective. I personally dislike Android and wouldn't use this phone if you gave it to me for free, but I can still respect the price for hw. I'm surprised this even needs explaining.
Have you ever used Android 4.2? This phone ships with a new OS version that I don't think is out anywhere else yet. How do you know in advance that you will subjectively not like it? I hate Windows Phone 7, but I wouldn't dare say I hate Windows Phone 8 since I've never seen it IRL. How could I make such a judgement? It's not purely subjective, either. What's the point in having more RAM or a bigger screen if the OS doesn't handle those well? Or, if it handles it exceptionally well, that should be noted as well.
