Galio's Ultimate is too situational
I understand and like the reason for Galio's ultimate. It is meant to save an ally from certain death, or in other words, counter-engage. Plus, its thematically accurate to Galio's lore. He wants to protect and make a heroic entrance.
However, its not the most reliable ultimate or form of counter-engage in the game. If you were to compare Galio's global ultimate to Shen's, the more reliable ultimate would be Shen's. For the reasons it travels WITH the champion and it does not have a limited range that scales with level.
More of the story, in my opinion Galio's ultimate is too situational. It does not compete with other Global ultimates as well as Shen's or Pantheon's.