Everything the review says happens actually happens. Multiple times, in most cases. Though it isn't as gory as some seinen manga, the violence is fairly intense and very pervasive.
As far as quality, I would say that HxH is on the upper end of shonen. It isn't making any masterful point about society or overflowing with complex metaphors, but it is more entertaining and intelligent than the vast majority of available series. If you like action in manga but also rational thought, I'd say it is worth your time.
As far as comparisons... sadly, all that is coming to mind is the latter part of Yu Yu Hakusho, the manga-ka's previous work. Obviously HxH resembles a lot of other action series, but not many have the same analytical flavor.