Depending on the time frame you are referencing, the Stock Market return has been great, horrible or something in between. It's important to understand, time can be considered a diversifier similar to diversifying across different assets and securities. Being invested across many different types of securities and across several asset classes is akin to using time to reduce risk, risk goes down with time.
It's important to keep Stock Market returns and Time in perspective.
In less than a month the Stock Market is up over 27% from the recent bottom.
Over the last 3 months the Stock Market is down about -13%
Over the last year the Stock Market is essentially flat.
The Stock Market is up almost 50% in the last 5 years.
In 10 years the Stock Market is up over 190%.