Is this about 'sehnsucht'; in which case, can God be Pleasure manifest or is he a being who is full of pleasure? "I have tried since . . . to make every pleasure into a channel of adoration. I don’t mean simply by giving thanks for it. One must of course give thanks, but I meant something different . . . Gratitude exclaims, very properly, “How good of God to give me this.” Adoration says, “What must the quality of that Being whose far-off and momentary coruscations are like this!” One’s mind runs back up the sunbeam to the sun . . . 

If this is Hedonism, it is also a somewhat arduous discipline. But it is worth some labour.”

This is from 'Letters To Malcolm' by CS Lewis. I assume he is, once more, talking about 'joy'/sehnsucht...an ineffible longing for we know-not-what but something 'hinted' at via beauty/pleasure. 
But, using God as Lewis's 'Sun' metaphor, is he saying we shall experience God as being the white heat, if you will, of all pleasure that we may/shall experience...or is he saying that God is a person who is full of happiness and goodness as a characteristic rather than his actual material substance and 'energy' he automatically gives off?

Appologies if this seems another whacky question, it's just, well, I like that kind...
I believe he is saying that God is a person who is full of happiness and goodness.  Namely Love love for all mankind.

He uses every experienced pleasure as an opportunity to give gratitude and contemplate the majesty of God.  The God of all creation.  

As can be seen here:  

Adoration says, ‘What 
must be the quality of that Being whose far-off and momentary coruscations are like this!’

He continues:

If I could always be what I aim at being, no pleasure would be too ordinary or too usual for 
such reception;

I think he is implying that if we could keep that mindset, even the most mundane every day pleasures or experiences can be opportunities to bring us closer to God through adoration which in turn enriches said experiences.

However it's not always easy to keep this mindset, obstacles such as inattention to the wonders around us.  Or choosing to ignore God's role in said experiences.  Lastly Greed Conceit.  Not being grateful. e.g.

that others would condemn as simply 'grey' the sky in which I am delightedly observing such delicacies of pearl and dove and silver.

In Summary:

What sparkling flashes of God’s wit and brilliance—His coruscations—have caused your mind today to 
run back up the sunbeam to the sun and given you cause to give thanks and to worship the Lord?

There is a children's hymn which is sung at my church that I think fits nicely with what C.S. Lewis is trying to get across here.

Whenever I hear the song of a bird
Or look at the blue, blue sky,
Whenever I feel the rain on my face
Or the wind as it rushes by,
Whenever I touch a velvet rose
Or walk by our lilac tree,
I'm glad that I live in this beautiful world
Heav'nly Father created for me.

He gave me my eyes that I might see
The color of butterfly wings.
He gave me my ears that I might hear
The magical sound of things.
He gave me my life, my mind, my heart:
I thank him rev'rently
For all his creations, of which I'm a part.
Yes, I know Heav'nly Father loves me.

Link to music

Link to CS Lewis Letter