I enjoyed the final two episodes too, although I am vaguely aware that lots of people didn't. It was nice to see Merlin finally doing some serious magic and coming out as a sorcerer, and also, hurray! Some Saxons have finally turned up. I'd been wondering if the whole Saxon side of the story had been dispensed with. I was disappointed to see that the Merlin Saxons weren't colour-coded with huge fluffy sheepskin vests, like Arthur of the Britons Saxons though. Actually, possibly that suggests one thing that would have improved Merlin as faintly-cheesy Arthuriana. It was very jolly, but it contained no Brian Blessed, and although Merlin's Percival's enormous arms were probably comparable to Brian's as Mark of Cornwall, there was no comparable bellowing.
I did wonder what exactly Morgana had done to win the everlasting devotion of the Saxons so that they were so willing to send an army at her call. Possibly I missed that, but my guess would be that these particular Saxons are just really into invading... everything. I am not even sure if any of them got names. England, founded by an army of nameless henchmen! There's a heritage to echo down the centuries.
The last episode of all was an extended two-day post-Camlann death scene, with Merlin playing the Bedivere role. This might have seemed a rather gloomy way to end if it were not, well, post-Camlann Arthuriana, and therefore never likely to be a bundle of laughs. At long last Arthur found out that Merlin had been stage-managing his entire career with illegal magic. He coped with the revelation surprisingly well, considering, and the whole 'you killed my father : prepare to die!' thing never came up at all, although possibly that was because of the 'dying of a splinter from an unearthly blade that is working inwards' aspect (where have I heard that one before...?)
Seeing Merlin as a sorcerer who actually sorcels full time, rather than a servant who sorcels furtively on the side, made me realise why the series has hung on so desperately to the idea that Merlin's magic must be a big secret, to the point where it was hard for the viewer to understand quite why nobody (particularly Arthur) had worked it out yet. As soon as Merlin turned up and started hurling lighting bolts, the entire Camelot army was suddenly rendered obsolete by superior technology. It made me wonder how they would have written a Merlin is revealed as a sorcerer plot earlier in the series - compared with Arthur, Merlin is shown as cleverer, mostly better informed, and with a better understanding of ordinary people, so you kind of wonder what there would have been left for Arthur to do, other than hang about looking regal and securing the succession. Although I suppose that is essentially much of the role of the British monarchy today.
I really liked the final little scene with an old, present-day Merlin walking past Glastonbury Tor (where he had left Arthur many centuries/one scene previously). It suggested all sorts of intriguing ideas for a Once and Future King return, without promising anything too definite. Although of course, you could see that Glastonbury Tor is no longer an island, raising the old questions about whether they found the Lady in the Lake when the drainage work was done, whether she was annoyed about being drained out of a home, etc
etc. And in this particular case, whether the Sidhe are still living there, and if so whether they are now running some sort of New Age teashop full of dreamcatchers and incense holders.
Oh, one final thing - was the 'Guinevere crowned as queen music' the same music that Aragorn gets crowned to in Return of the King? Is that official TV Coronation Music now? It sounded very similar!