Every once in a while, I come across an adaptation that renews my faith in adaptations. Log Horizon is one of those. It's patient, faithful, improves on the original instead of crapping all over it, and it's simply good. It covers the first 5 volumes of the light novels, each volume given approximately 5 episodes (most LN adaptations give 3, max 4 eps for one novel - explains why most LN adaptations are crap). The adaptation is faithful (though I've only read the 5th novel, so I'm not entirely sure how faithfully the first 4 vols are adapted), with slight improvements on the pacing and comedy and replacing some of the slightly excessive amounts of inner monologue and narrator explanation with dialogue - shows that the director not only respects the original material, he also understands what needs to be changed when transferring the story over to another medium.
Everybody knows that the concept of Log Horizon is very similar to that of the widely popular Sword Art Online, on paper. What everyone who has watched/read both knows is that in reality, they're nothing alike. IMO, LH is much better. But I haven't watched SAO completely, so I won't go any further with that comparison.
A more interesting comparison, in my mind, can be made to a korean webtoon manhwa called The Gamer. These two stories have the opposite approaches to essentially the same theme. The Gamer plays with the idea of what would happen if a live human were to become like a game character, while remaining in the real world, only applying game logic to his life. He gains experience, his physical and mental attributes are determined by his stats, he kills monsters and gains loot, he can learn skills by reading a book etc. Log Horizon, on the other hand, takes place in a virtual game world, which the human players eventually discover to be more alike a real world than they ever imagined. In many ways, real world logic applies to that world. I can't say much more without spoiling important plot points, but I really find the comparison between these two works quite interesting.
But enough about adaptations and comparisons, let's talk about the anime and its own merits. One of the first things you'll realise when starting to watch it is that Log Horizon is rather slow-paced. There's some action, but it never really takes the spotlight, this story is about something else. It's mostly about discovery, settings building. This is achieved without all that much travelling, for what is discovered here is not so much what lies beyond the horizon, but more about the rules that govern that world, and gaining a deeper understanding of its indigenous people - the NPC's. That's some freaky advanced AI that controls these NPC's, they're so much like living humans that players can befriend them, or fall in love, before they realise that the other party isn't a player character.
Another very interesting element in the story is politics. I don't know what it is in fantasy politics that I so much enjoy (I care little about real world politics), but LH is one story that serves me well in that regard. Just as the main character's intelligence serves him well in this new world he's found himself and 30,000 other players. I do love an intelligent protagonist, perhaps even more than a badass one. Shiroe would have no need to be ashamed in the company of characters such as Keima from The World God Only Knows, Tooru from Iris Zero and the nameless protagonist of Hammer Session. He's a masterful organiser, manipulator and strategist, who is awesome enough to change the very rules governing his new world.
Other than Shiroe, there are a few other characters worthy of notice. First of all, Crusty and princess Leinessia are a pair whose interaction is in the highest class of entertaining, IMO quite comparable to Lawrence and Horo from Spice and Wolf. The two maidens holding special feelings for Shiroe, Akatsuki and Minori, also gain quite some development during the story. And then there's one more very interesting NPC character, whose identity would be a spoiler. There are plenty of entertaining and likeable characters besides them, but honestly, I feel like characters overall are a weak point in the story. They avoid archetypes pretty well, but they're not given much depth either.
The plot is... great. It manages to be unpredictable and entertaining without being overly complex or twisty. But what is perhaps even more impressive is how little it relies on action. Similar to the author's earlier work, Maoyuu Maou Yuusha, there is a measured amount of action, but its role is strictly limited to supporting the plot. It's a bit more reliant on comedy, but in part that is thanks to the adaptation - the original novels have somewhat less comedy. Furthermore, if the anime adaptations are any indication, the author has greatly improved from the days of Maoyuu. LH has a way, way more interesting story to tell. A story about building a society out of a more or less lawless bunch of gamers lost in a familiar yet foreign land, and as I said earlier, about discovering the rules governing that world. This story is clearly settings-oriented, but it's a different kind of settings building from what you usually see in similarly oriented fantasy stories.
I might have rated the anime 9 or 9.5 points, if not for the unfortunate fact that the 5th volume happens to be a breather between two more serious arcs. Had the anime ended at 20 episodes, it would have had a properly climatic ending. As it stands, the last arc is interesting, but rather lacking in excitement - not a good finish, it leaves far too mild an aftertaste. It does give us a glimpse of what to expect from the second season, however, and somebody had the good sense to ensure that there WILL be a second season, so that it's not just another annoying incomplete story -ending. Still, the last arc would have served better as the start to the second season.
The visuals are good, but nothing worth talking about. The VA's are good as well, but nothing outstanding. The BGM's aren't bad, but probably not worth DL'ing either. The OP and ED, however, are both great.
In conclusion, Log Horizon is a great anime with fantastic settings building, a likeable cast of characters and a quality plot. It squeezes far more out of its basic concept than I thought possible. It's not for everyone, as there is a significant lack of ecchi and the pacing is pretty slow for the most part, but for me those are positive facts. I score the anime 8.5/10, due to most of the supporting characters being somewhat shallow and the ending being anticlimactic.