There are lots of technical discussions of the EMH...and lots of qualifications made. How does it impact your life, though? Here's the line:
There are other people playing the stock market who are (a) smarter, (b) better informed, and (c) more devoted to it than you are. This all but guarantees that index funds (Falkenstein: low volatility index funds) give you a better expected return than any other investing strategy (and once you count trade-costs, it's a slam dunk).