Fans of the novels, beware. People who have not read the novels, watch at your own peril.
This anime has none of the quality or story-telling people have come to expect from the past few years. Production values obviously fell by the wayside, or otherwise all the money for animation is being embezzled by an unscrupulous director. In addition, they have rushed through FULL NOVELS of storyline in just a few episodes, in an anime that should have had a real focus on war and peacetime tactics, as well as economics (not to the depth of Spice and Wolf, or MaouYuu). If you are going to watch this, do so in the knowledge that you are giving yourself spoilers and/or the highlights reel from a series of books you should READ.
And for those of you who think I'm just a literary snob - that's fine. But there have been some very good adaptations. Log Horizon, for instance. SAO had more in the series than the original set of novels! There are examples of good adaptations out there, this is NOT one of them.

Enough flaming. This is a mediocre adaptation, but it has some merit. Though fans of the already established novels may not like this, it certainly is good for a first time watcher, despite glossing over many details in the opening scenes, the battle for Tigre's home, his relationships with the older characters as 'mentor-like'... It is exciting for newcomers to the franchise, and with battle tactics playing a large part of the story, it is a good watch for war-buffs and the like.

As mentioned, the animation is lacklustre, but is improving as the series continues, with fewer misshapen attempts at facial expression and less palette mismatching. The fan-service is a little overdone, though there are fewer instances of 'ecchi mistakes' in the series than in the books.

The music sets the right tone for the series, and has elements that place it firmly in the fantasy genre. Perhaps a more medieval tone could have been applied, but that is more personal-preference than a problem. There are no notable themes running through the series with regards to music, but the series isn't over so we can probably expect a good climactic instrumental to accompany any action scenes that appear later in the series.

The sheer depth of storyline of the books makes an anime somewhat prohibitive in character development. Many characters have been given far too much screen time vs. character involvement, but that may be to do with the voice actors and their demands, as well as the overall direction by the producers. Voice acting is good, and reflects the characters' strengths and weaknesses well - the girls are perhaps a little too cute at times, when their respective positions in society should only allow such a thing in private. But that is included in fan-service...

Overall, the quality of this anime is lacking, but the story from which it comes makes up for the poor effort on the production side. Worth a watch if you:
1. Haven't read the books
2. Like war themed movies/shows
3. Don't mind flashing-back to the mid-1990s in animation quality (at the beginning of the series)
4. Want a harem that is implicit rather than explicit