Being able to draw multiple cards a turn (or even during your opponent's turn, which in fairness is one area that this is better than Necropotence, which is regarded as one of the most powerful cards of all time) is a huge advantage, and the cost is completely irrelevant until you are actually in danger of losing the game and therefore can't risk paying it.
If you draw 19 cards off it, leaving you with a single point of life, you probably ended up drawing 10+ more cards than your opponent and are so far ahead that you aren't at any risk, or already won the game long ago.
It's pretty good, though overcosted now.
Being able to draw multiple cards a turn (or even during your opponent's turn, which in fairness is one area that this is better than Necropotence, which is regarded as one of the most powerful cards of all time) is a huge advantage, and the cost is completely irrelevant until you are actually in danger of losing the game and therefore can't risk paying it.
If you draw 19 cards off it, leaving you with a single point of life, you probably ended up drawing 10+ more cards than your opponent and are so far ahead that you aren't at any risk, or already won the game long ago.