Tried it, loved it. You HAVE to hold it and get a sense of the phone. It's difficult to explain what a difference build quality means unless you experience the product. I use an iPhone 5S and if there's one thing I could change, it would be the sharp edges. The One M8 fits perfectly in your hand.
For those of you in Singapore, it's available tomorrow, 5th April at all major telcos for S$998 without contract. Oh yea!