Hmm. The last couple of times this ability's been seen, it's been restricted to creature spells: Glimpse of Nature, Soul of the Harvest. Before that, it did apply to all spells, but it was a 6-mana enchantment with a hefty drawback: Null Profusion, Recycle. Also consider that this is like the best bit of Future Sight, but applying to the cards you draw normally as well.

All in all, I suspect even as a 4-mana 1/1 this is rather undercosted.

It probably is, although in a closed environment where you don't expect a deck full of Lotus Petals, it could be okay if you expect this to draw 2 or 3 cards at most before it's killed. 4 is winning the lottery.