I read this play for about the seventh time and realized that I have nothing to say about this play because it doesn't surprise me anymore. Or maybe I have too much to say about it and don't know how to filter it down to what's important.
So I'll go ahead and compare it with Romeo and Juliet, a play written around the same time as Midsummer. Both seem to be "about" the madness of love, as it were; Midsummer has a comic resolution, and R&J a tragic. But in both plays the illogic of the lovers' choices and/or actions is made clear. Romeo is hasty and desperate; Juliet has no discretion, choosing Romeo over Paris. The lovers in Midsummer act hastily, escaping from Athens into the woods at night; and we have two male lovers who, for all intents and purposes, are the same person--the moody, dreaming lover.
In both plays there are themes of parental choice vs. personal choice in love. Romeo and Juliet cannot marry because of their feuding families; Juliet's father forces her to accept Paris, whom she does not love. Hermia and Lysander are forbidden to marry, because Egeus has already given his daughter's hand to Demetrius. In the play-within-a-play, Pyramus and Thisbe face almost the same problem as Romeo and Juliet, with similarly tragic consequences.
But both plays also seem to highlight the idea that accidents, or fate, can be just as powerful as human choice. In R&J, the lovers make Plan A, Plan B, and Plan C, scrapping each plan as new circumstances take shape. But despite all their planning (and all their conspirators helping them along the way), accidents line up so that they each needlessly commit suicide. In Midsummer, the lovers make their choices and swear up and down that they will have none other than their chosen love--and then fate, in the form of fairy king Oberon and his servant Puck, show how arbitrary and circumstantial those choices are as they trick Lysander and Demetrius into falling in love with the "other" woman (cf. Daileader). Titania undergoes an even more embarrassing magical transformation, falling in love with someone not only arbitrary but embarrassing.
It seems like the theme seems to be, in both plays, that love makes fools of us all. And love is a force of danger. Not only Romeo and Juliet, but also Paris, die for love in R&J; in Midsummer, tragic events are barely forestalled because Lysander and Demetrius definitely want to kill each other and Helena and Hermia fight it out as well. Hermia herself is under sentence of death from the beginning of the play as Athenian law stipulates that if she does not comply with her father's wish, she can be killed. And let's not forget the violence inherent in the relationship between Theseus and Hippolyta: "I wooed thee with my sword and won thy love doing thee injuries" indeed! And when love goes wrong, as it has between Titania and Oberon, seasons, crops, weather patterns are affected--the entire natural world is under siege.
But in each play, love is also a restorative force. After Romeo and Juliet's deaths, the Capulets and the Montagues stop their vicious fighting. After the love-spells have worn off, each lover is with his or her appropriate beloved. Three nuptials are celebrated and a fourth, the reconciled Titania and Oberon, crown them all with fairy blessing that restores everything to the natural order. And this paradoxical nature of love--its destructive AND restorative powers--are referenced in both plays.
The fairy presence is also an interesting through-line. I'm not sure I really "get" Mercutio's entire Queen Mab speech. I see why it's interesting and I understand what he's saying, but I don't really know why it's there (unless as a way for good ol' $hakespeare to show off his versifying). But I heard some really cool Mab resonances in the description of Puck that is given; he is also known for creating mischief and illusions, for playing tricks on people.
Midsummer is a typical comedy in its multiplicity of plots, whereas R&J follows one plot. There is more low-class humor in Midsummer as well; the only lower-class citizen in R&J who seems fully integrated into the plot is the Nurse. She and Bottom have a lot in common, though; both garrulous story-tellers who are, in some ways, the "heart" of the play.
Finally, both plays employ lush love poetry and lots of rhyming dialogue. I'm partial to the poetry of Midsummer, though, because it is so full of flowers and plants and the moon. It is just lovely!