Here's the thing? I enjoyed the show for what it was, but it had it's share of flaws. The first arc, or the first 14 or so epsiodes, were fine and dandy. The world set-up was great, the characters were more of less entertaining (if they weren't Kirito), and it was fun and enjoyable, for the most part.
I find that I actually liked every single character more than Kirito. I don't hate him or anything. It's just I didn't really feel attached to him, at all. Hell, I felt more attached to Suguha, and she stole the MC roll from him for a good while during the second arc. My favorite character had to have been Asuna (Liz being a close second) because of how she was presented. She was strong and mostly independent (unless the writers demanded she wasn't, like during that stupid incident with Kuradeel and forgetting she could pull rank) and I felt more for her more than any other character.
I think if the show had ended at episode 14, then it would have been fine as it was. Heathcliff's motive for making the virtual world wasn't nonexistent I'll admit, but by saying I forgot what it was, then that just feels like a major copout. I realize he wanted to create a new virtual world paradise, and that's fine, but why do it at the expense of 4,000 people's lives? Honestly, if Heathcliff's reason for this was more concrete, the first arc would have been fine. Don't get me wrong, some stupid contrivances were required for the first arc to proceed as it did (like a good number of them in episode 3's party death), but it wasn't all that bad honestly, even if it did feel like .hack//lite sometimes (especially during Yui's introduction.
And then the second arc came in the form of ALO. And it was terrible. Because when the second arc hit, it felt like we jumped off the rails and went into an entirely different genre and turned into a different show altogether. It also didn't help that it introduced Suguha's incestuous desires for her brother/cousin Kirito. Like, the stark contrast between SAO and ALO's arcs are just amazing.
In SAO, PKs were considered murderers. Kirito lived in a world where the virtual world WAS the real world, for the better part of 2 years. He was traumatized by the deaths of his party members in the first guild he was part of, and he only killed when he absolutely had to (Heathcliff didn't really give him much choice on the matter)... and then ALO happens. ALO, which runs on the EXACT SAME ENGINE as SAO did. It seems sort of hypocritical for Kirito to vow never to let his party die while also being okay with killing others.
What really pulled me out of the story for ALO? It... seems like a downgrade in terms of scale. SAO had ten-thousand lives on the line and the players were trapped in the game for a solid two years before clearing the game (and that was a fluke!). However, for the second arc, it's mostly only Kirito's problem. Granted, the villain's motivation for ALO was much better (mind control research is a great research), if not a bit creepy (oh god episode 24 was terrifyingly close to jumping into a straight porno at times). I just didn't feel it. I enjoyed the fights yes (aerial combat is almost always amazing).