Every series has its filler, and every set of filler episodes for a series has it's truly terrible couple. This wasn't awful. Not great, not particularly good, but not awful.
I've kept quite quiet this series - mostly I can find the time to watch the episodes, but that's stretching it, and the time to comment and read other opinions never materialises.
There was some good humour (I liked the exchange between Uther and Arthur at the beginning), but there was also some pretty childish humour (Elena).
Merlin has never been a serious series, and nor is it written to appeal to the older ones amongst us. It's in that early evening Saturday slot for the Hollywood fantasy genre of series to keep the younger ones happy. The better humour is put in to keep the parents ever so slightly amused.
Every series, when it isn't in filler mode, has good episodes, and next weeks looks like that - no silly effects, no fart jokes, rather we're given good old-fashioned choreographed swordplay and an evil force (and as an evil force, Morgause is quite good at it).
Personally I think it's a foolish idea to give up on a series because the filler wasn't to your taste - it lacks direction for quite an obvious reason... If you're going to pack it in, do so once the main story arc episodes turn out to be utter drivel.