Books. Merlin wasn't Arthurian legend. They just redressed Smallville with little sword and sorcery. Now if you want to watch almost Merlin but better but made on a budget for 12 year olds, in the way that the Sara-Jane Adventures was sometimes better than Doctor Who, season two of Leonardo finished about a month ago, which was just awesome. http://www.imdb.com/title/tt1745588/?ref_=fn_al_tt_1
I've seen this show up to the end of Season 4, so I don't really know what happens in S5 yet. I too thought it was basically Smallville made by the BBC. On that note, it was entertaining if you knew to expect the same level of writing as Smallville. As a plus, Merlin didn't "permanently" lose his powers every 3rd episode, only to regain then right at the nick of time, thru some contrived loophole in the story. In this aspect, it was better.