So far I've done two firmware updates (1.7 and now the 1.8).
The 1.7.??? went ok, and the DJI Do APP said it was successful. However, after checking the TXT file on the SD card, I found out the update had actually failed (that was the root-cause of some erratic flight maneuvers).
Yesterday I updated again to 1.8.??? and this time everything went fine. I did check the TXT file, and in there it said the update was successful (nowhere on the DJI site, it says to check the file on the SD).
What I found to be a 'foolproof' way to update is like this:
Since the controller and tablet communicate over WIFI (P3S), the WIFI connection needs to be changed a coupe of times to connect to DJI-Go, then download from the web, then re-connect to DJI-Go to go actual firmware update. This was the very 'flaky' point about the whole process.
This time, I used a tablet that had a cellular connection on it, so, while the controller maintained the WIFI connection to the tablet, I downloaded the firmware through the cellular network, and did the upgrade without having to swap networks. Worked fine!