I disagree there. I found the S4 disappointing, when it could have easily met or exceeded my expectations.
1. Build materials and quality. Having used the Xperia Z and HTC One, they absolutely blow the S3 out of the water, and will blow the S4 out of the water. There is no reason why Samsung couldn't have gone with a premium material for the phone build. Sony and HTC seemed to have put in the effort to make an excellently designed/manufactured device, Samsung just rehashed their materials/design. People will want to say it's because of the removable back - there are phones that are made of metal and have removable backs, hell Samsung made one (Wave), so that excuse is out the door. Having owned an S3 and removing the back a few times, I started noticing cracks on the plastic which is not comforting at all.
Samsung have more money than Sony and HTC put together. Absolutely no excuse why they couldn't have made a premium feeling phone.
2. Screen. I know AMOLED is their thing and the colours are highly saturated, but I personally prefer the LCD3 screen in the One and even the LCD in the Sony screen. Given that LCD screens have more accurately calibrated colours, better battery life while web browsing, can get much brighter (which greatly helps sunlight visibility, especially in Australia) and less prone to burn in - I would have preferred a great LCD display over AMOLED.
3. Legacy button layout. The physical home button and 2 capacitive buttons were fine and dandy with the Galaxy S and S2, but now times have changed and I think Samsung should really focus on pushing tech forward with adopting the stock on-screen button layout of Android now.
4. Performance. I have concerns about the performance of the phone. Android Central had a hands on, which showed laggy screen swiping, GSM arena had laggy screen swiping and Gizmodo's impressions said that the HTC One was faster than the Galaxy S4 in every context. Could be due to early software/hardware, but that doesn't sound good at all for a high-end Android phone.
5. Samsung's direction. Watching the abysmal S4 presentation, I feel like Samsung is more focused on a phone store experience rather than a real-world phone experience. The phone is packed to the gills with gimmicks and it seems more designed for a customer to be wowed by all these 'features' at a phone store then them actually being used outside of one. It seems they're only focused on that initial wow factor to grab the sale. I had the S3 and things like tap-to-top and smart stay didn't even work properly for me, let alone be of any use.
These are just my opinions, and I know not everyone will share them, but they are the biggest issues I had with the S4. As such, I'm not interested in getting one as competitors have more attractive products to me.
On a side note, I find it hilarious that Samsung had commercials mocking Apple for using the same design with the iPhone 4S "If it looks the same, how will anyone know I upgraded?", when Samsung have essentially done exactly that:
http://img.gawkerassets.com/img/18hhpxvf0ao60jpg/original.jpg