In Macbeth by William Shakespeare, the first time we hear of Macbeth is in an account of his exploits in battle. Specifically, we learn that he "unseam'd" someone "from nave to chaps." He is victorious in battle, and we presume he is happy about that.
The first words Macbeth speaks, however, offer us a kind of mixed signal when he says, "So fair and foul a day I have not seen." The witches immediately appear, and Macbeth is a little confused by their pronouncements as they hail him Thane of Cawdor and "king hereafter." Before he and Banquo can even digest that strange event, King Duncan's men come to proclaim Macbeth as Thane of Cowdor.
It is all a little overwhelming and confusing for Macbeth, and we still get some rather mixed messages from him. He says:
Cannot be ill, cannot be good: if ill,
Why hath it given me earnest of success,
Commencing in a truth? I am thane of Cawdor:
If good, why do I yield to that suggestion
Whose horrid image doth unfix my hair
And make my seated heart knock at my ribs,
Against the use of nature? Present fears
Are less than horrible imaginings:
My thought, whose murder yet is but fantastical,
Shakes so my single state of man that function
Is smother'd in surmise, and nothing is
But what is not.
Just as Macbeth observes that this news cannot be good and cannot be bad and that "nothing is but what is not," his feelings are rather confused at the bewildering things that have just happened. He does say that the news has made him fearful, which is not a characteristic of happiness. He cannot be properly be called happy or unhappy, it seems to me.
The next time we meet Macbeth he is with King Duncan, and he speaks and hears kind words, but he is dismayed that Duncan has just named his oldest son, Malcolm, as the heir to the throne. Immediately Macbeth says this is
On which I must fall down, or else o'erleap,
For in my way it lies. Stars, hide your fires;
Let not light see my black and deep desires:
The eye wink at the hand; yet let that be,
Which the eye fears, when it is done, to see.
He leaves to go home because Duncan is coming for a visit and he must get there before him. Somewhere in the midst of all this activity he writes a letter to his wife. In it we find the first real indication that these happenings have made him joyful. He writes that he wanted to tell her the good news right away
mightst not lose the dues of rejoicing, by being
ignorant of what greatness is promised thee.
Once he gets home, of course, there is little time for celebrating. Lady Macbeth has already planned that they will murder Duncan while he is here and starts insulting Macbeth for his hesitancy.
Looking at the evidence, then, it would be hard to claim that Macbeth was a happy man when the play begins, despite all of the positive things that happen to him. While he has a few moments of happiness, he is more befuddled, afraid, and confused than either happy or sad.