If you are reading this review, and you want to play the new 4th Edition D&D, you have come to the wrong place.
Unearthed Arcana was written in 1985. I was about 10 years old and was playing AD&D, which consisted of the Player's Handbook, Dungeon Master's Guide, Monster Manuals 1 and 2, and the Fiend Folio. That year however, Gary Gygax and Jeff Grubb decided to try to add a further dimension to the 1st Ed game.
This game not only adds dimensions, it adds a number of "fixes" to the game to raise problems that had come about from the initial books.
Problem 1 - the level limits for non-human characters were too low. This book addresses this by giving higher ability score characters higher limits. (GOOD)
Problem 2 - the fighter subclasses do not have distinct enough roles. This book separates the Paladin to become a subclass of Chavalier, and the Barbarian becomes a new class of fighter. Therefore, we have the "knight" style classes, Chavalier and Paladin, and the "warrior" classes - Ranger and Fighter, who get weapon specialisation, and the "tanking" brute class the barbarian. (GOOD)
Problem 3 - charisma is not physicial attractiveness, but personal magnetism. Solution - introduce (redundant) seventh attribute = Comeliness. (BAD)
Problem 4 - characters not heroic enough. Solution - make uber powerful characters who are rewarded for rolling high ability scores. Encourage players to cheat or do anything to raise ability scores. (BAD)
It appears that after Unearthed arcana, for all its great new spells, magic items, class changes, and variation of the races (now you can play a Drow = dark Elf, and history was never the same again) fuelled the creation of mega-powerful characters. Ability scores rise in importance. The new race subtypes add an element of richness into the characters that was welcome. The new classes were generally good (with the exception of the comical Thief-Acrobat) but a DM might wish to be cautious before introducing all the changes here. However, this book is full of something that I see lacking in the newer volumes of the D&D products - imagination.