Does it work in competitive Constructed play? Green/Black Constellation decks during the Journey into Nyx Standard era could use it. Heroic decks could use it, too, especially those that used a lot of Auras - which are also Enchantments. But, the Helm never really fit into any of those lists.
Also, the Standard decks in Standard which could have used the Helm best when it was released lost all of the Theros cards a few months later in October 2015. However, with the release of Dragons of Tarkir, SaffronOlive of MTGGoldfish came up with a Standard "Bogles" deck featuring Conifer Strider and Sagu Mauler. It used the full four copies of Helm of the Gods and was a fairly fun deck. But, it wasn't a big winner or anything.
Bogles decks in Modern could use it. But, again, it doesn't fit in what is already a deck vulnerable to dead draws. Modern Prison decks could find a slot or two and stick it on one of the few creatures in the deck. But, that is hardly a top tier deck, and it's more like cute tech than a true upgrade.
Helm of the Gods in Commander / EDH
In 60-card Constructed decks, there isn't much room to give. In Commander, though, Helm of the Gods can fit into a variety of decks because you have 99 slots to consider. Also, Commander decks have plenty of ways to tutor for it. Trinket Mage can grab it, being a one mana artifact. Being an equipment, Quest for the Holy Relic, Steelshaper’s Gift, Stoneforge Mystic, and Stonehewer Giant can also seek it out. You could get it with the creature Relic Seeker from Magic Origins, too.
The Helm is a card that gets better as you go through the game. You just play it as soon as you need it. It could be a game-ender, and even a +2/+2 boost is worth the investment. Unlike an Aura, an Equipment is usually going to stick on the board when the equipped creature is gone.
Immediately what comes to mind are Commander decks with a heavy Enchantment theme. This includes Tuvasa the Sunlit, Daxos the Returned, and the hated Zur the Enchanter. It also includes Voltron Aura-loving commanders like Bruna, Light of Alabaster, Krond the Dawn-Clad, and Uril the Miststalker. With such a minimal commitment of mana, the Helm could deal those last few points of Commander damage you need for the win. It can go on any creature, though. Any Commander deck that loves enchantments can use the Helm.
Helm of the Gods will never be a money card, but bigger and better enchantments are printed all of the time in Magic the Gathering. If an Enchantment-happy deck is going to be in play for you, the Helm at least needs to be in your deck-building toolbox.