About the play itself so much has already been said I don't reckon I can add anything meaningful in a blog post. Shylock the Jew is the most prominent part, the marriage plots serving mostly as a foil for his intriguing character. Shylock and his bond (lending money against a pound of Antonio's flesh) add depth and significance to what would otherwise have been just a fluffy comedy.
As per usual, Shakespeare dipped joyously into existing plays for inspiration, Marlowe's The Jew of Malta being one of his sources here.
(And to those of you who believe that this in any way diminishes the Shakespeare genius : All of the others did the same, at the time; none of the others had Will's skill with words, his psychological insight nor his staying power.)
Regarding this Arden edition (edited by one John Russell Brown), it offers a standard, instructive introduction and notes that are so extensive as to be virtually useless, at least if you are reading the play for mere entertainment.
I think I might dig out my old dvd of the Al Pacino version, just for pleasure.