I tried a Keurig at my local bank (free) last spring and was impressed. I then got a Platinum (which I think is top of the line for the residential variety) at Costco a month or two later. I haven't yet gone back to my more conventional machines.
Yes, it is more expensive. But it does brew excellent coffee, IMHO. I use mostly the Paul Newman brand K-cups. They are rich and flavorful. Donut Shop is ok too, but I prefer the Newmans, which are only slightly more expensive than the Donut Shop ones.
I've also tried the adapter that allows one to put in any loose coffee grounds. It's ok too, but does take away one of the prime benefits of the Keurig: the convenience.
As far as being inundated with ads, haven't seen that here. I believe that Keurig's patents are running out in a few years, after which anyone (like China?) could start making and selling them, so maybe Keurig's management is busy trying to amp up sales before that happens.
As for the machine, it's very well made and designed, really a joy to contemplate. They did a very good job on this one. I've even been tempted to get a second one to bring to work, since it's so much more convenient and makes so little mess (loose coffee can get all over the place).
In any case, I give the Keurig a thumbs up for those who drink only one or a few cups a day. If you're in a pot or more a day habit, then I would suggest a more conventional method.