Yep, Domination is my personal favourite game mode, and is our go-to format when we have an odd number of players. We've enjoyed discovering the power of Altar of Skulls, Akiro's Hammer, Elusive/Flying creatures, zone-effect spells, and creature swarms - cards and archetypes that aren't as strong in regular Arena.
Arena is still generally our 2-player mode of choice.
If you ignore the intent of the product (eg toss out the rule book) and just look at the cards, Academy is a pretty good expansion for Arena and Domination. I think the next 2 Academy Mage expansions will do a lot to make the Priest/Priestess and Warlocks more competitive in Domination, for instance. Right now they struggle to keep up with the board presence that the (Bloodwave) Warlord, (Straywood) Beastmaster, Druid and Necromancer are able to achieve. The Forcemaster and Wizard are kind of left out of the Donination mode (at least for multiplayer) - but that's OK, as they're certainly competitive in regular Arena.