once upon a time they had a great product, and they made it terrible by forcing annoying advertisements in all their menus, as soon as you pause anything, over live tv when a product is featured, and they don't provide digital over the air programming info for non-cable subscribers. 100% of customer contact goes through a call center which is powerless to perform all but the most basic tasks.
/rant
that's odd. I've never seen an advertisement whenever pausing live TV, or when pausing recorded shows. Yes, there's a 'more about $foo_show' item that pops up, but I clicked on it exactly once years ago and never noticed it again.
I'm unsure about the OTA programming thing, but since the device is basically geared to be a 'cable box replacement'. It has a niche and it's a good one.
All the times I've called the TiVO call center (it was in Canada, I believe) the techs were quick, gave good answers to my questions, and even help me grandfather in my USD12.99/mo subscription on to my Premiere device.
I've used MS-based DVR's in the past and was shocked at the poor quality and glaring usability problems.