I bought this to replace an Arris SBG6580-2 that had issues with frequent resets and lockups (apparently not uncommon according to reviews) after a few months in service. The Motorola MG7550 is designed in large part by Zoom, and I've had good results with Motorola/Zoom products in the past... and the reviews of the MG7550 gave no reason to think otherwise of this unit.
I'm familiar with programming home routers, including features like WiFi MAC access lists, port forwarding, firewall rules, DDNS, and DHCP address reservations. I had all of the necessary information on hand, and I thought getting the MG7550 set-up would be a relatively quick process. The user interface was easy enough to navigate, with on-screen contextual help available for just about every item.
Getting the modem activated with Comcast/Xfinity was a quick online process. I then started to program the MG7550's features... and that's where things started to get dicey. Although I was finally able to get everything working properly after several hours (I learned to back up the configuration after each significant change was finally successful), I experienced many inexplicable quirks in the user interface that made what should have been a straightforward process pretty painful. For example, when making entries for DHCP address reservations, all entries except one would enter properly but that one particular entry would cause the DHCP server to switch itself to "disabled" (with the only apparent recovery being a factory reset "start over"... hence the frequent backups through the process). Finally only changing the name of the device I was trying to enter for a DHCP reservation allowed the process to complete. Also, my DDNS entry reported that the DDNS provider was unreachable until, after one of many times cycling the DDNS feature off and back on again, it decided to suddenly work. My guess is that this all reveals a "not ready for prime time" graphical interface behind which is a pretty solid machine.
At the end of the day, the MG7550 is working well, with good WiFi coverage for a unit with integrated antennas. The WiFi scanner is a very helpful tool in selecting WiFi channels/bandwidths. Hopefully some updates are forthcoming that will improve the usability of the programming interface... the bad news is with this being a modem/router combo, you're at the mercy of your cable provider as to if or when you'll receive any available updates.