After a overall great show, a fairly decent fifth series and a very good first part, you can really see they more less wanted to end the show, which would have been fine if the series actually would have gone in that direction. The series, however, in no way tries to end the show but rather to work as another series with a few more coming up in the next few years. While the first part of this story still works as a regular series finale, which usually take the main characters to a point they never were in before and that actually questions if they could make it over the episode, the entire plot of the first episode is concluded in the first five minutes of this story and replaced by ONE HOUR of Merlin trying to save Arthur's life, only to FAIL in the last five minutes. This finale is probably one hour of the worst writing I've ever seen. The entire plot builds up to something that simply doesn't occur, and that's not even the entire reason why this episode is so awful.
For example, what was the entire Gwaine plot about, where Gwaine seeks out Morgana only to be captured and killed? This entire sequence only serves as a plot point so Morgana would be able to locate Merlin and Arthur. That's right: They killed of one of the fan favorites only to have a cheap twist that brings the antagonists back into the Merlin-Arthur-story. Meanwhile, the fact they were written out of that story for so long only serves as a way to include the magic reveal as pure fan service. What would be the point of Merlin revealing his secret, if not fan service? The way they killed of Mordred simply shows how this episode simply doesn't care anymore, since they wanted to end the show anyway. They built up this character for the runtime of the entire show, especially this series, and he is just killed off within the first five minutes?! This get's even more extreme, as Morgana, an almost immortal evil witch set up for the entire runtime of this show and in all that time couldn't even get hurt by entire armies, is simply killed off by Merlin with Excalibur. This is probably the worst way to kill of this character, especially since Gwaine and Percival tried EXACTLY THE SAME a few minutes earlier.
Besides all the plot holes this episode has, I have to address the complete piece of sh*t that the speech of the dragon was. Even though Arthur was far from even scratching the legend he would be once, he suddenly achieved everything he was supposed to?! And when talking about the ending: What was that old Merlin scene in the end about? To conclude this review: The entire episode clearly shows the writers simply didn't give a f*ck to make the finale decent in any way. They simply tried to end this show as fast as possible, and while the series had a great setup, the payoff was more than disappointing, it was simply insulting the fans of the show. After five series, they didn't care for anyones opinion anymore, since no one would continue the show anyway.
I give it a 2/10, simply because despite all this flaws, some of the setup to the end we would've wanted to see was made quite decent, but what is a decent setup worth if it just doesn't lead to anything?