Of course, such a book has suffered the pass of time, as the writers acknowledge in later prefaces. I skipped several sections entirely; there's one chapter devoted to listing which communist literature of the time was any good.
As for the rest, I found it much easier to read than I expected, even if the first chapter could be basically summarised in "the bourgoise are the root of all evils". There were a few interesting thoughts; he explains why the previous revolts have failed and how the workers have played in the bourgoise's hands.
You could have some laughs, like when he argues that communal women are totes fine because the rich are sharing their wives already anyway. I wonder if they ever asked a woman what they thought of such a thing. But of course! We don't count. I bet Engels did have a hand in writing that section.
All in all, it wasn't too bad, but it's hard to see how this book became so influential. (It was funny reading Engels basically wondering the same thing, though).