Playing one side of the card doesn't mean the other remains permanently out of reachit just means you have to pay the mana cost of the other side to 'unlock' that room later
If you can hardcast it and your deck is capable of holding off Burn and Abzan decks on its own, you'll find this very powerful whether it's in the opener or not
A large burst of mana plus three fresh cards often leads straight into a combo turn or a massive swing
Additionally, if your deck has a lot of card draw or even just manipulation (your Commander Scrys or draws, for example, or you're Mono-Blue with a ton of cantrips and Ponder-style effects), you can adjust your number
In 2013, the best price for the Unlimited version of the card was still under $1,200
Be wary of Counterspell and Spell Snare before casting key spells, and avoid overextending into Supreme Verdict