Is This Helpful or Needlessly Pessimistic?

As an aging man, and one who had been a Christian for over 30 years, John Newton had this to say about his experience:

At my first setting out, indeed, I thought to be better, and to feel myself better from year to year; I expected by degrees to attain everything which I then comprised in my idea of a godly Christian. I thought my grain of grace, by much diligence and careful improvement, would, in time, amount to a pound; that pound, in a farther space of time, to a talent; and then I hoped to increase from one talent to many; so that, supposing the Lord should spare me a number of years, I pleased myself with the thought of dying rich in grace.

In other words Newton expected to grow exponentially in his faith.  You can imagine that there were various sins of the heart that Newton figured he would have conquered within 30 years time.  Not only that but there were certainly a good number of graces that Newton had hoped to “improve upon” within this time.  Yet this was what he discovered:

But, alas! these my golden expectations have been like South-Sea dreams! I have lived hitherto a poor sinner, and I believe I shall die one! Have I then gained nothing by waiting upon the Lord? Yes, I have gained, that which I once would rather have been without, such accumulated proofs of the deceitfulness and desperate wickedness of my heart, as I hope, by the Lord's blessing, has, in some measure, taught me to know what I mean, when I say, "Behold I am vile!"

The core of what Newton learned was that he is more vile than he imagined.  If he stopped there this would be obviously depressing.  There is really no benefit in acknowledging our sinfulness and wretchedness if we don’t look to Christ the remedy.  Admitting human need is empty application unless God’s provision is simultaneously exalted.  And this is what Newton does:

And, in connection with this, I have gained such experience of the wisdom, power, and compassion of my Redeemer; the need, the worth, of his blood, righteousness, attention, and intercession; the glory that he displays in pardoning iniquity and sin and passing by the transgression of the remnant of his heritage—that my soul cannot but cry out, "Who is a God like unto you!"

Still, my question to use is this: Do you find Newton’s testimony here helpful or needlessly depressing?  Is he denying the image of God and work of the Spirit in his own life too much?  In his desire to exalt the work of Christ on the Cross is he at the same time casting a dark shadow on the work of the Spirit in the Christians life? 

I’m interested to read your comments…   (I’m hoping to get opinions from both sides).