It always puzzled me a bit that my English friends seemed to have a better knowledge of Shakespeare's history plays than I did, and only now has the obvious answer occurred to me: they are all about English history, which my school had a natural bias against giving too much importance. As a result I knew almost nothing about the two parts of Henry IV except that Falstaff is a character.
Well, I'm enlightened now. This is a good play: essentially the education of young Prince Henry, under the two possibilities of ending up like the unhealthy drunk and cowardly Falstaff or the valiant young Harry Hotspur. The Falstaff option is vividly illustrated by highway robbery; the Hotspur option by rebellion. In the end, the Prince kills Hotspur, yet in a sense takes on his mantle.
It's a bit unfortunate that this gets mixed up with politics. The rebellion against King Henry is even more obscurely motivated than most, and it is one of the few unsuccessful rebellions in the canon. The Welsh angle is a bit peculiar as well, with actors instructed to "speak in Welsh" in one scene. Perhaps this is scene-setting for Part 2.
The Arkangel version has great performances from Julian Glover as Henry IV and especially Richard Griffiths as Falstaff. Alan Cox is good as Hotspur, but unfortunately Jamie Glover as Prince Hal doesn't quite seem to get the point of blank verse; I hope he improves over the course of the next two plays.
Henry VI, Part I | Henry VI, Part II | Henry VI, Part III | Richard III | Comedy of Errors | Titus Andronicus | Taming of the Shrew | Two Gentlemen of Verona | Love's Labour's Lost | Romeo and Juliet | Richard II | A Midsummer Night's Dream | King John | The Merchant of Venice | Henry IV, Part I | Henry IV, Part II | Henry V | Julius Caesar | Much Ado About Nothing | As You Like It | Merry Wives of Windsor | Hamlet | Twelfth Night | Troilus and Cressida | All's Well That Ends Well | Measure for Measure | Othello | King Lear | Macbeth | Antony and Cleopatra | Coriolanus | Timon of Athens | Pericles | Cymbeline | The Winter's Tale | The Tempest | Henry VIII | The Two Noble Kinsmen | Edward III | Sir Thomas More (fragment)