There will be games when this is good, of course, but most of the time your opponent will either have a removal spell (and make it a 5/5 so they can kill it) or will have a way of dealing with it or ignoring it in combat (and make it a 3/3 so they can forget about it)
At the end, I'll preview a powerful and exciting new card from Magic Origins
Timing this one is tricky, as theres definitely some tension with when you should play it (earlier is better for the mana rock aspect, but it could lead to you answering irrelevant threats)
For just two mana, you get out of committing to a single effect, and now have as many as you have in your graveyard
[21] The "Boons": Healing Salve , Ancestral Recall , Dark Ritual , Lightning Bolt , and Giant Growth