When Dictate of Heliod was first released, a lot of Heroic deck builders wondered if this Enchantment would trigger Heroic abilities. Because Dictate of Heliod does not target, sadly, it did not. However, it didn't stop this card from seeing play even in some Heroic Aggro decks that sometimes just needed a slight boost to win the game. But it really was more of a mid-range card during its Standard lifetime. And while the effects of additional copies of Dictate of Heliod do stack, it never really made sense to run more than one copy in a 60-card deck.
Considering how good this card turned out to be in Standard, it's no surprise that it sees regular Commander play. Token-happy Commanders Rhys the Redeemed and Trostani, Selesnya's Voice adopted it quite quickly, although not to the degree that you might expect. It hasn't become a staple for any one Commander.
The Commander who has best adopted Dictate of Heliod is Daxos the Returned. The Enchantment-happy commander can spit out of a lot formidable tokens with his ability. Being an Enchantment, the Dictate gives you an experience counter when cast. This makes the tokens that Daxos creates much more powerful. The extra +2/+2 power and toughness boost is certainly helpful, too, but not quite so much to make it a staple in his decks.
Another Commander that has made good use of the Dictate is Iroas, God of Victory. The Journey into Nyx red and white God has seen fit to play Dictate of Heliod in about a third of his lists. Since he gives creatures you control the ability to only be blocked by two or more creatures (known as Menace), giving your creatures a significant +2/+2 boost can be quite relevant. You can really blow out an opponent's blocking plan by bringing in the Dictate at Instant speed.
While Dictate of Heliod never became the Commander staple that some members of the EDH community predicted, it's still a great toolbox card. It's also a card with beautiful artwork, and that means foil copies could be a nice little investment. It's actually surprising that Dictate of Heliod's foil price was still little more than $1 even towards the end of 2016. This is a card that all Commander players should have in their deck building toolbox. It's an anthem that doubles as a combat trick, and if you're running any White creature-heavy Commander decks, it's one to consider.