Hegel's Phenomenology of Spirit is doubtlessly one of the most influential works of philosophy ever compiled. Briefly summarized, Hegel 'retraces' (so he says) the dialectical movement of consciousness from mere sense-perception, through reason and into Spirit; and he makes significant analogies to the history of philosophy, religion, and indeed history itself.
It is hard to understate the influence of this book. Hegel offers a rather compelling and imaginative account of the development of collective human thought, particularly beliefs, values, and ideas; and his notion of history as teleological has inspired many thinkers, revolutionaries, and reformers who proceeded him.
I have several warnings. First, it's far too enthusiastic to call this the 'be all and end all' of philosophy. I strongly warn against getting carried away by Hegel's ideas. Hegel is guilty of making enormous leaps in logic, of obscurantism, and of syncretism. You must approach this with criticism, otherwise you'll earn nothing. Further, you shouldn't take his historical analogies as bare evidence - I don't think even Hegel meant them as such - for they aren't linear or even very accurate. They're better thought of as illustrations, not evidence. And, again, you shouldn't get caught up in Hegel's mystical language. Hegel wasn't a mystic but a true believer in reason, although reason brought him to some pretty strange places.
I must say, however, that this translation left me a little disappointed. I recommend you get a German copy and refer to it regularly. No translation is perfect; but there are many things wrong with this one. The translator rarely explains what words he is translating in footnotes or brackets, although there are many, many instances where they would help greatly, e.g., as an indication of what certain pronouns - which are gendered and thus more recognizable in German - refer to. Further, I was very much annoyed by his rendering of 'Begriff' as 'Notion': although it may be translated as such, I find it far too mystical and fuzzy and I think 'Concept' would suit it far better. Its one advantage over the older translation is its rendering of 'Geist': the latter renders it as 'mind,' the former (more correctly) as 'Spirit.'
In the end, I definitely recommend you read this book; but I warn you that it'll be one of the hardest you'll ever read, especially if you're not acquainted with philosophy. I suggest you also get a guide book of sorts: I found several at the library and used them all heavily. And, again, I recommend you get a German copy (if you can understand it) for cross-reference.