As someone who was initially skeptical of both 4E (thankfully wrong here, the game is terrific and well balanced) and of DDI, I am not impressed by the latter's choice of payment options and auto-renewing billing.
The price is certainly right, for about $5 US per month on the yearly billing, but there is no good reason to use this slightly shady auto-billing option with no obvious way to cancel it. D&D'ers who are likely to purchase DDI are probably more tech-savvy than the average 'net consumer, and such decisions by WotC do them no favors in attracting potential subscribers like myself.
I am loving 4E so far, but the DDI content is far behind where it was promised to be and this billing system seems to be rushed out the door. I was initially going to subscribe, but after this I will wait and see for awhile.
WotC, I'm one of your "buy everything" customers (books, minis, map sets, etc.) and I'm not happy about this. A strong, transparent billing policy for DDI will attract and retain subscribers like myself. This slapdash way of doing it, though, will keep me away.