yup, no guide right now can tell you exactly how they work... pretty much...
STR gives you a +2 base ATK, which in the formula is rumored to be divided by 15.53, so this means that in order to increase your Skills power by 1 base point, you need 15 STR.
INT is the same story, but it is rumored to give +3 base MATK instead.
AGI is the one in charge of boosting up your Hit/Dodge relation as well as your Crit rate. So far it is known that a 600 points difference in Hit/Dodge results in a +/- 20% Hit chance aproximately. As for Crit, it used to be related to level, now it is indiferent of such parameter and seems like 1 AGI point = 0.045% Crit or so... not very sure.
WIS increases your SP, and as of late, they designing the skills so they would actually consume your SP so SP pots gets more weight. This stat will also be in charge of reducing elemental damage, but thats yet to be implemented.
VIT boosts up your HP, so far only Beasmasters benefit from this stat adding them some extra DEF points.
Currently, all classes benefit the most from AGI, since gear gives loads of the other 4 stats, but in the end it is supposed to be for personal preference.
Base stats were supposed to be scaling in price per level, but now they only costs 1 point regardless of how high you get them.
By reaching level 50 you'll get 75 points, passing through the Master Levels and hitting level 20 you'll get 100 more points, and you can buy up to 100 stat points scrolls too. So thats 275 stat points.
It is uncertain which is the current stat cap (used to be 50)