Like many others I have upgraded a Asus RT-N66U
to the RT-AC68U, there's absolutely nothing wrong with the RT-N66U but my decision was based specifically on upgrading to USB 3.0. I have a 2Tb Hard drive full of Films, Music and TV programs connected to the Router and they can be streamed to any device connected to the Wi-Fi, even my neighbour who shares the connection with me streams the films and documentaries to her laptop on regular basis. The USB 3.0 port enables me to transfer files to the hard drive 4 x faster than before. The Router also has a 2nd port which is USB 2.0.
The set up is very simple, intuitive and it connects in minutes, the only thing that slowed it down was having to input the BT connection details, once done the wizard connected in seconds. As soon as it connected The RT-AC68U automatically updated it's own firmware to the latest version 126.96.36.199.374.4561. The 5 GHz and 2.4 GHz wireless set up is also very simple, name the connection give it a password and away you go. If you do want to use the 'MAC filter' which is a feature that will only allow certain MAC addresses to connect to the router, it might take you a minute or 2 longer to add the addresses. It may be an idea to have a note of all the MAC addresses of the devices you want to connect, although once they are connected you can easily add them via drop down menu before you activate the filter. The button on the rear of the unit that disables the blue LED's is a welcome addition, on the RT-N66U I had to place a piece of tape over the LED's to stop my bedroom becoming a disco at night.
The range is fantastic, I'm getting slightly more coverage than the RT-N66U and it seems to be more responsive and snappier on the wireless devices, I was shocked how quickly web pages loaded on my Galaxy S3 while I was next door. I have a number of devices connected and there seems to be no noticeable lag on any of them while running them at the same time.
1 x Desktop (Hard wired)
4 x Smart phones
2 x iPods
4 x laptops
1 x iPad
1 x PS3
I've not had a single drop out or disconnection since it connected on 10th March.
I'm on BT Infinity (fibre) and use the RT-AC68U in conjunction with the BT modem (Supplied by BT) so obviously get exactly the same speed I did on the RT-N66U.
The only thing I'm slightly disappointed about but it's not enough to take a star off is the change in orientation, I preferred to lay the RT-N66U flat on some drawers with the antennas down the back but I did buy the RT-AC68U for it's performance and not how it stands.
From reading other reviews I have noticed that some people have not done research into what the Router is actually capable of doing and when they receive the device are disappointed. The RT-AC68U is an expensive piece of kit so who wouldn't check it out first to see if it did what you needed it to.
I suggest viewing the "ASUS RT-AC68U Router Overview" on YouTube [...]
EDIT: Please be aware this review is for ASUS RT-AC68U and not the Asus RT-AC3200 which this review is also appearing with.