Its nice that the card stays on the battlefield, generating more value, attacking and blocking, and that the removed enchantment doesnt return (its not an Oblivion Ring variant)
Remember that all cards can fluctuate in value and change drastically over the course of the release weekend and in the weeks to come
It seems to me like the more Spear of Heliods and Boartusk Lieges the Horde uses, the less useful Glenn becomes, and with only one copy, it will likely come out after the anthems/buffs
Since then, many older cards with this ability have retroactively been given deathtouch
Lifegain can put a hamper on your plans, so Roiling Vortex's ability to prevent lifegain for just one mana is crucial in shutting it down
The Game is pretty much over