party play pre-lvl 60 is still ok as sometimes u need tank if u're playing dps class and if u're a tank u need dpser in your party.

upon reaching lvl 60, u will try to solo first. and when u found out its hard for u to solo, u try to party. it'll pull u through until a certain point where u know u have to make a decision. to farm gold or to farm items.

if u have crap GF/MF, u will want to find ppl with good GF/MF to party with BUT ppl with good GF/MF invested a lot of money and time to get those gears. partying with a person with low GF/MF doesn't seem like a good idea for your gold investment since the person with high GF/MF would reap more benefits from solo-ing and it takes longer to kill the mobs since the HP doubled up already.

i still do party with my friends and we're at act 3 now, and we facing a brick wall. when that happens, we go into farming mode for better gears and we will party together again to see if we can break through the wall.