One disadvantage of the Mediatek MT6753 chip is that its integrated modem doesn't support LTE Cat 6, only LTE Cat 4 (150 Mbit/s). With LTE Cat 6 the device can connect to two bands at on and aggregates the bandwidth of both bands to offer faster download speeds. By the way, the Meizu M5 does support LTE Cat 6. So it's definitely a disadvantage.
The Cat LTE antenna can access 4G on the higher frequency 2.6GHz band, which translates to a whopping download speed up to 300Mbps, doubling the Cat 4 capabilities. The ability to connect to two spectrum bands at the same time is a great advantage for those are in need of a very wide bandwidth, mainly to consume multimedia content. So it's the different between 150 Mbit/s limit and 300 Mbit/s limit that makes the Meizu M5s less attractive for those who search for a phone with 4G+ LTE Cat 6 speed on their phone.