From a reputable company (like Celestron) it ought to be ok. However, if anything goes wrong (filter burns through, cracks, drops out) the damage will will like

From a reputable company (like Celestron) it ought to be ok. However, if anything goes wrong (filter burns through, cracks, drops out) the damage will will likely be irreversible. Think of it as the risk of standing at the wrong end of a loaded gun. Even if you avoid looking directly at the sun, it's possible to make mistakes. On a transit of Venus I was having trouble getting a telescope lined up, so without thinking I bent down to have a look through it to see where the sun was. Luckily the resultant burn made me whip my head back before my eye got to the eyepiece.