Easier how?
Login to email, Send email. Recieve Email.
Click on PMs, Send PM, Recieve PM.
Doesn't seem overly different
PM's are used at all major OC'ing and PC forums, they make communicating on the forum much quicker and easier than email and make a single point of contact. However for buying and selling they have the added disadvantage of:
a) Having a limited space. When PM box is full you can send no more to the recipient. No use if someone can't be arsed to clear out their PM's and you need to contact them urgently.
b) If someone doesnt log onto the forum then they don't read them... they are easy to avoid.
However the fact is OCUK will not activate them due to the "zomgcompetitor" paranoia, so
moremoney you need to use email, period.