Shakespeare's A Midsummer Night's Dream is a well-loved comedy. It would have had a profound and positive effect on theater-goers of the Elizabethan era for several reasons.
The most important element is that of the supernatural.
...during the age of the living Shakespeare, the Renaissance...practically every type of written word deals with the supernatural.
Much like people who go to movies today to be scared to death, the Elizabethan audience would have been drawn to this play because of the presence of fairies and changelings. They believed in both. And while they would have been frightened of the evil witches in Macbeth, they would have been highly amused by the antics of the members of the "fairy kingdom." In their belief of such creatures, they all knew better (for example)—as Bottom seems to forget—than to walk in the forest after dark. For then one was at the mercy of the fairies, who were not seen as evil creatures (because of how Shakespeare presented them), but entertaining and mischievous. They would play with "mortals" simply to have fun. Puck talks a great deal about this when he is first introduced into the play.
When Bottom (an "actor") wanders in the forest, he becomes Puck's dupe—in Oberon's plan to torment his queen, Titania.
What hempen home-spuns have we swagg'ring here,(70)
So near the cradle of the fairy queen?
What, a play toward! I'll be an auditor;
An actor too perhaps, if I see cause.
Puck discovers men (practicing a play they hope to perform for the Duke's wedding) near the place where Titania sleeps, and decides use Bottom in his plan. Bottom leaves the "stage," and returns with the head of a donkey; he frightens off his fellows (who also believe in fairies); he is there when Titania awakes under a magic spell—she falls in love with the first thing she sees...Bottom, head and all.
The lovers in the story (around which the tale revolves) are also affected by this magic potion when Puck gets confused. In an attempt to make Demetrius fall in love with Helena, who adores him, Puck mistakenly uses his magic on Lysander, so he no longer loves Hermia, but Helena.
You do advance your cunning more and more.
When truth kills truth, O devilish-holy fray!(130)
These vows are Hermia's. Will you give her o'er?
I had no judgment when to her I swore.(135)
Helena doubts his sincerity, but Lysander says he was crazy to love Hermia. When Demetrius wakes, also now in love with Helena, Helena has had enough, thinking they are making fun of her.
O Helen, goddess, nymph, perfect,
To what, my love, shall I compare thine eyne? (140)
O spite! O hell! I see you all are bent
To set against me for your merriment.
If you were civil and knew courtesy,
You would not do me thus much injury. (150)
Now both men love Hermia—where before, neither did. The confusion creates a wealth of hilarity, often delivered with a great deal of "slapstick"—or physical comedy—as well.
Elizabethans believed that if the fairy world was out of balance, it would affect their world—the seaons, for instance. So Titania and Oberon must make up for the humans.
This play is ultimately about love: Hermia's love for Lysander (and his for her), Helena's love for Demetrius (which is eventually returned), the Duke's love for Hippolyta, and the love of Titania and Oberon. It is also about a play within a play.
The audience would have loved the humor, the supernatural, and the comic characters.