This review relates to the Penguin Classics version which comes with an "Introduction" by Gareth Stedman Jones. I put "Introduction" in quotes because it is about 180 pages long, whereas the pamphlet it is introducing is about 30 pages.
If you are interested in reading the Communist Manifesto, it's well worth getting this one, rather than saving yourself a few quid on an edition which just contains the Manifesto itself. Without putting this book in its historical context, you're likely to find yourself thinking "so what?!". The intro is academic and dense at times, but well worth the effort.
The most enlightening aspect of the manifesto itself, for me, is what is NOT in it, rather than what is. There isn't a description of how a communist society should look, for starters. The story of this book is the story of a pamphlet written for a specific time and place, which became an iconic work when it was seized on by the Soviets for reasons of political expediency. I'm sure if Marx and Engels knew what they would turn this book into, they would have written it very differently. No wonder Marx is quoted as saying "I am not a Marxist".