Being objective... is not.
Sure, its better than the old one... it has a new VO that is cool, good particle effects and a new recall... but if we compare him with any "new" Legendary skin: Gatekeeper Galio is bad.
Many skins have new recalls and particles, which means that having that its not a big deal (more if we consider that all the champions have recalls now)... In other hand, most of the new legendary skins have a new VO. However, the diference between Gatekeeper Galio and other "New" Legendary Skins is that the other Legendary skins actually have new animations in everything.
So, in terms of content, even if Gatekeeper Galio is way better than his old version, he is not comparable with other legendary skins like Omega Squad Teemo or Mecha Sion... and lets not even talk about Ultimate skins.
... Also... if we talk about References in the VO, Final Boss Veigar is the king.