Well, after two weeks living with the phone I thought that I'd best report back with my experiences and thoughts of it so far.
I have to say that in day-to-day usage this thing is awesomely fast. I don't care what any benchmark tests say, in general use this is just as fast (if not faster in many instances) than the HTC One that I had for a month - probably due to the N4 running stock vanilla Android. Being vanilla android, this will be one of those handsets that is always being tinkered with in order to personalise slightly more - arguably part of the appeal of android anyway.
The handset looks premium and feels good in the hand. My initial concerns about it being fragile have been put aside as it lives inside a Ringke Fusion case which offers plenty of protection for what I need plus the clear back shows of the beauty of the handset - personally I actually find it easier to handle than the HTC One.
I'm a lot happier with this handset than I thought that I ever would be - the fact that it is almost half as cheap as anything else of a comparable spec is just the icing on the cake for me. The display is great quality and responsive and the screen is a delight to use and very smooth. The battery life (for my use) is brilliant - I'm not a heavy user but it is looking like lasting almost twice as long as the upgraded battery in my old HTC Sensation used to! The camera is not the greatest, but it is far from being "bad", it's just not particularly special to either use or look at the results afterwards - acceptable is probably the best way to describe it.
Now, my only real gripe - and this is not a fault of the phone. Coming from HTC, the Sense UI integrates everything into the contacts list seamlessly and brilliantly - Facebook pictures, status updates, phone numbers, addresses, e-mail addresses etc etc. The stock Android Contacts app is shockingly poor in both looks and ability as standard (Google - NO-one uses Google+). I am still on the look out for a decent contacts app that would mimic that provided by HTC if anyone has any suggestions. I'm currently using Contacts+ which is okay but anytime I use the wife's Sensation I'm reminded how poor the other contacts apps are.