Overall I liked it - but then I do normally like episodes which move away from "monster of the week". Hopefully the events that take place might move things a little bit on (as in they don't reset for the next episode).
Acting wise I do agree the whole cast has got more into their characters, with the younger actors shaping up nicly, though again we have the older leads stealing the show.
A few things though did stand out.
1) The guards part - as mentioned above - two things come to my mind here, the first is that they are eating near a bridge, so I am guessing they are not so far out in the woods as it might seem and thus the need for a heavy guard presence is not that great. Also whilst we only have a week often many more have passed in the story between episodes, so whilst it might seem that only yesterday they had massive bandit problems it might already be old news as far as the kingdom is concerned.
2) The Magic - honestly I think if one wants more meat to the magic it would have to come from a book, in TV land and with the pace of the merlin series I don't think they could put too much more detail in before they would start to lose the pace and thus the style.
3) Marrage in 1 day? Ok I undestand the magic is powerfull, but I think this should have been moved to a week at least if not two - it just seems very strange that the kingdom (and characters like Arthur) could accept and prepare for a wedding of their king in so short a timespan. This could have been done with shorter scenes and more buildup - with Gaius coming to his conclusion later in the timespan rather than at her arrival. That would have made things a little more belivable
4) Arthurs fight with the servant - I would have prefered this to have taken place outside of the main castle area, it just seems a little loud and noisy to go unnoticed - rather like Arthurs appearance in the hall at the end (though thank the powers he didn't do an "I Object" bit I was dreading that happening!