provide your thoughts on the likely appeal of Marxist socialism

provide your thoughts on the likely appeal of Marxist socialism to Industrial workers in the 19th century.  What are the most persuasive points made by Marx (and/or Engels)?  What might be the unintended negatives of their views and how they might play out in the real world with real people?  Is there anything in Marxist ideas that still find useful in explaining conditions in the world today-why, or why not?