Well hello. I'm partially bias because I read the books first and I loved them. That being said I hope this will be as objective as possible. I will give examples of the episode in particular but if some great development happens I keep quiet.(Sorry if anything is misspelled)
Story: The introduction to the story was very well done in my opinion. After a while it started to slow down around the middle and it picked up again. The way they introduced the main plot twist was very well done in my opinion but I feel that, even though all the basis were covered by the first episode, it would have been better to make a longer first episode. I believe that there is no problem with the series caching up with the books because in the books there is a time-skip. If the developers take the time to do each floor, and all the side-stories that have been made, than the series will be on at least as long as bleach.
Art: I really enjoyed the art style used because it gives a MMORPG vibe, at least to me. It also makes it very easy to make the beautiful childish world of Aincrad, the name of the virtual game world, into a scary place. I was personally scared during the system announcement but I'm pretty spokish so...
Sound: I personally don't pay much attention to the sound, unless there is an epic piece of music playing, but I felt it really helped with the mood, changing at exactly the right moment.
Characters: I really liked all of the characters. I found them likable and I could understand there dilemmas, at least the one showed at the end of the episode. I hope that they expand on all the characters because in the books I felt that they where kind of shallow, with the exception of the 2 main characters, but that will be seen in later episodes.
Enjoyment: I was entertained the whole episode but there were some moments that I wished they would pick up the pace. That being said these were few and I am a very impatient person.
I believe this will become a great series, if they pick up the pacing it will be excellent, and I'm really looking forward to later episodes.
Overall: 8.6 rounded up to 9.