The reality is that the card can be great once you're already online with your strategy, but is probably less efficient at setting that strategy up
You'll virtually always have a spell to cast with this, which gives you a 2-for-1 up front -- and will trigger everythign with Flurry
They provide the highest level of mana consistency, especially in multicolor decks
Keep in mind that Doubling Season is the card that synergizes the most with counters and tokens
Generally speaking, its easier to buy the singles you want rather than open packs and hope for those specific cards
The fact that you have to wait a turn, attack with it, wait another turn, and then untap it (or combine it with something) and pay two to get anything done will keep this from the big boy tables