I really really enjoyed the series.
As someone who has played more than his fair share of MMORPG's in the past, and the idea of what it would be like if I actually lived in the game has crossed my mind more than once, this anime really appealed to me from the get go.
The mix of characters, both good and bad, are enjoyable and I really liked the way Kirito and Asuna are very believable as people, stuck in a crazy situation, manage to cope and retain their sense of identity and who's feelings eventually grow towards each other.
The supporting characters really help to build the world, for both the very sad depressing moments as well as the happy joyful moments.
The dub for this is excellent, so watching dub or sub is a matter of personal choice rather than which one best shows the excellence of the anime.
Not all of the episodes have been dubbed yet, and paying the crazy prices that retailers are asking for just a few episodes each time is extortion. You can buy the whole subbed series on DVD for just over £20 so why nearly £90 for all the separate dubbed episodes? I will wait for the complete box set of the dub to come out rather than buying the series piecemeal.
To conclude, I have given this series 5 stars based solely on the actual series itself, as it is really enjoyable. I would give 1 star for the cost they are asking for.
EDIT: All the episodes have now been dubbed. I watched the series a while back before they had finished dubbing. Apologies.