based on http://www.crossfire.com.sg/faq/faq01.html:

Not really. The paintballs are designed to break open upon impact.
You will most likely feel a sting from the paintball hitting your
skin, but it doesn't really feel much different than a wet towel
snap.
and

Paintball is one of the most injury free records of any sport.
Insurance statistics rank it as less of a risk than even golf, or
bowling. Like any physical sport, it has itsÂ’ risks. However, if
proper safety procedures are followed carefully and proper
equipment is used then paintball can be very safe. The most
important rule to follow is to use a mask designed specifically for
paintball. Goggles, glasses, or any other eye protection not
designed for the sport WILL NOT work. Your eye is the only part of
the human body that a paintball can permanently damage. Never play
paintball without wearing the proper protection for your face, and
your eyes.
.. we tot it is not that dangerous. plus, u never know until u
try it out.