The X-wing being blown up does look just a tad dodgy.
After watching the clip a few more times, I think I know why; it's because there are no evasive maneuvers or any sort of reaction to being shot at -- the X-wings just fly in a straight (or slightly curving) line and there's no return fire or anything (I know that there's not much point in shooting at a Star Destroyer if you're in an X-wing, but it still looks odd).
Otherwise, it looks really, really good.