It's funny. I've been using a Note 3 for a few months, rooted with a custom TW firmware. I recently took out my old M7 and realized how much faster and smoother the user experience is. I am not talking about how fast a app opens, as I am comparing a S600 vs a S800 chipset. The Note 3 clearly has much more power. Yet TW still stutters, even with 3GB of ram. Hell, even overclock and it still skips.
The same is with the S5. People who claim there is no lag haven't used a M7/M8 or a Nexus 5. Its pathetic that people have to wait for a custom rom or kernel to get their device operating as it should be. This is why I am skipping out on the S5 all together (for the record I have used one, on several occasions). That and absolutely no development yet. Samsung continues to disappoint, and reminds me a lot like Apple.
Those little "hiccups" that so many people are actually accepting, take a look at this video. This ties into the fluidity of the OS, and how much smoother the M8 is. One thing not mentioned here is how much faster opening up the recent apps opens up on the M8. Also, the S5 will shut down apps in the background while the M8 keeps a lot more open at a time.
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Samsung Galaxy Note 3 - DD, Acer C710 W/16GB Ram/64GB SSD/Dual Boot Ubuntu/ChromeOS
Moto X # 2 - Sold, HTC One - Sold, Nexus 5 - Sold, Moto X - Sold, Galaxy Note 2 Titanium - Sold, Optimus G - Traded for a case of beer, Nexus 4 - Sold, Galaxy Note 2 White - Sold, Galaxy S3 - Sold, Galaxy Note N7000 - Sold, Galaxy Note I717 - Sold, Samsung Galaxy S2 LTE - Sold, Samsung, Galaxy S2 - Work, Motorola Razr - Sold, Motorola Atrix - IN PIECES