Good points and bad points
Good
Low investment for small resellers (75$), still get same rate as larger resellers.
Low domain registration fee.
buying a whoiscart.net license for just $35 means 24 cent reduction on domain registrations, worth buying it even if you aren't going to use it.
API is actually quite good
Bad
Poor Customer service
Poor / buggy interface
Some features aren't included, but very rarely needed.
API poorly documented
The weird thing about directi is that it is very appealling to the small / first time domain reseller as they aren't punished for their low volume of sales, but because of poor customer service and useless interface they are the very people that should avoid this reseller.
I advise only experienced resellers to touch directi, but then again they will normally be able to get the same pricing with a far more reliable registrar.
So I guess the target is market is Experienced, low volume sellers and I doubt there's too many of those about.
I should also add, directi works quite well if you have a verified paypal account, if you don't and want to pay by credit card avoid them, they want everything barring a pint of your blood and your mothers false teeth to proove who you are.