The Galaxy Note 4 is awesome (just bought one for my daughter) no real contest with the iPhone6 really once you factor in the AMOLED screen, size, resolution, popping colours, proper blacks and not to mention, swappable battery, SD card slot, even if you don't want to use the S pen! Before I get a load of reaction from apple lovers, each to their own, live and let live! You have to choose what is right for you.
Anyway the point of this post is that I have just bought a Galaxy Note Edge to replace my Note 3. It is in 99% of respects the same as the Note 4 but the Edge screen is added. I (and many commenters on the Interweb) are not sure whether it is the future or just a gimmick. I personally find it very useful. The night clock is great - not too bright (or battery munching) to be annoying. The other options are great - especially if they are intergrated into apps - such as the camera controls and shutter button being moved to the egde screen - it really works well.
Samsung have issued an SDK so app makers can use it, and with the upcoming S6 slated to have one (maybe two!) it doesn't look like it will become unsupported and more apps should use it as time goes on.
Is it worth an extra 100 pounds? Well time will tell ,but if you want everyone to notice your new phone - it has attracted more attention already than any other phone I've ever had (and I am an 'early adopter' so usually have the latest) and some really useful extra functionality - then the Edge is the winner in my book.