No matter the version, HxH is my favorite shounen series of all time. This adaptation is my favorite despite lacking the new story arcs (:
HxH is categorized as a shounen in the database, but you better not start thinking about the latest episode Naruto n friends. This is far beyond any generic shounen trash. I've heard people describe it a disguised seinen, not gonna take cred for thinking of that but I totally agree. HxH doesn't constantly bullshit you, it's too real.
At first glance, the story might look extremely generic; boy trying to find his father yada yada, but don't judge the book by its
cover, you'd be doing yourself a disservice doing so in this case. It features some of the best storytelling that has ever come out of the medium, clearly much thought was put into it. It's a story I can happily wait 2-3 years between volumes to read, because I know it'll never disappoint.
So it might be looked at as as seinen disguised as a shounen, which you can tell by how little fighting there is. The fights in are sparse and short, but extremely memorable because of how they're built up and executed. The show builds up for some of these fights for several episodes, and the payoff is always so satisfying despite sometimes being short. Even when they seem the most pointless, you'll grow to appreciate them.
The characters are hella good too; Kurapika, Leorio, Gon, Killua, Hisoka, Chrollo and even the smallest of characters have strong presences. They each have their own unique motive and also their own hurdles to tackle.
The characters is a point where I think the 2011 version is lacking comparatively. The first arc of the show is double the length in the original series, and they take that time to make you feel more connected with the characters. You get to see them interact more with each other in ways not shown in the 2011 version. You also get to see key plot points which were neglected in the remake in favor of speeding it up to the more actiony parts. It's the biggest reason why I think people who only watched the 2011 adaptation should consider watching it, at least the first arc anyhow.
Now you might say something in the likes of: "Eww old art, unwatchable". If you don't like old anime, that's fine. HxH's art can definitely be off-putting to some, the color scheme tends to be very dark, and the animation is really wonky at times. But for the rest, you can enjoy one of the most atmospheric anime shows ever, in terms of both story and visuals.
In terms of animation, the actual characters are poorly drawn at times, especially in the first arc, but the show gets more consistently good art and animation as it progresses. Toward the end, I think the art is very well done and nice-looking. I much prefer the character designs of the 1999 version, they don't look so over-the-top as they do in the 2011 adaptation.
The animation itself one of the reasons for my 8/10 score. It pales in comparison to shows like Rurouni Kenshin and YuYu Hakusho which aired years before Hunter.
The soundtrack is awesome. It fits perfectly with the show's atmosphere. It truly is one of those soundtracks I can listen to all the way through without skipping.
I even went back to certain parts where nothing remarkable was happening, but the visuals and presentation made it awesome.
HxH has some of my favorite intros and outros, especially the second and third intros. The second in particular I consider to be a masterpiece, as it conveys what the main character of the arc goes through perfectly, and with such a distinct and neat style.
The sound effects are funky sometimes, like when Hisoka strangles Gon a balloon scratch effect plays, and you can totally tell it's just a guy scratching a balloon :_:
The animation and sound effects don't distract from the enjoyment for me, it's still a definite 10/10. There's hardly ever a dull moment in this show, especially when you take the time to invest yourself in the story.
TL;DR - Good story with solid characters, dope ass soundtrack and awesome settings with a dark and gritty atmosphere.
There are considerable differences between the adaptations, so you should watch both this, the OVAs and the remake. The OVAs continue the story where he 1999 series left off.