This is finally a worthy successor to the Tivo Series 2. While there have been 2 previous HD Tivos before, their relative cost and the lack of available options for lifetime subscription made them unattractive financially compared with the cable company DVR. If you purchase directly from Tivo, there is a (...) lifetime subscription option to those with a previous lifetime subscription. That makes this a worthwhile deal, even if it takes about 30+ months to break even.
If you've not used a Tivo before, I would say it is head and shoulders above Comcast's ugly, ill-conceived interface. If you've used Verizon, it will be a step up, but not nearly so dramatic. If you've used Tivo before, you'll feel right at home. It's basically the 8 year old Tivo interface that's been spiced up here and there, with supporting links to Netflix & Blockbuster for streaming movies.
This Tivo requires an M-Series cable card if you're not recording from an antenna. If you're not sure, call your cable company to see if they support it. Verizon did struggle with this question, although eventually I found someone to confirm the Verizon cable card supports multi-stream. However, the Verizon tech they sent was helpful and had the job complete in about 15 minutes.
Although the Tivo supports resolutions up to 1080P, it is only available at 1080p/24, so if you have a slightly older set that only supports 1080p/60, you'll have to drop back to 1080i. That isn't spelled out anywhere on Tivo's site, although it probably doesn't make much of a difference.
This Tivo networks nicely with older Tivo's allowing you to transfer video between them, although it's not possible to transfer from an HD Tivo to a SD Tivo, although the reverse works nicely. You can also use the Tivo Desktop (a free download) to transfer to your PC. You can even save it to watch later or on your portable (Google "kmttg tivo").
I won't write a review of the Tivo interface. More people have done it better than I could, so Google for reviews. You should know, although the new menus are in high definition, once you get away from the primary menus, it drops back to the old 480/SD menus. The only reason I can tell is the screen on the TV flips a bit until it resyncs with the lower resolution.
This version of the Tivo has a backlit remote, although by default that isn't turned on. It also supports separate volume and muting with an A/V receiver, although it doesn't give you the ability to turn it on with your remote. My A/V receiver did not work with the codes provided, but a chat with Tivo pointed me to a page on their support site where you'll find the new Tivo has a "learning" remote. That did the trick.
If you use Tivo's Chat support, the agents are well-informed and patient.
I've had one brief incident as I messed around with various menus where the HDMI lost sound sync with the TV. A quick resync through the A/V receiver got me back and running in a few seconds. Time will tell if that was a one-time glitch or a problem.
Previous Tivos have worked with Amazon video on demand (which works reasonably well). Now there are additional options to select high-def material, and you also have options to download from Blockbuster and Netflix. Keep in mind there is a charge for this type of on-demand movie, similar to what you'd expect from your cable company. However, this function is integrated beautifully into the overall search function. As an example, let's say you're interested in a program such as "Chuck". As you search for the program, not only will it find the upcoming episodes on TV, but will also present you with the complete episode guide, giving you the options to either record from cable/antenna, or for shows that aren't available you can download them to your Tivo to watch. That's very clever and convenient.
Overall, it's an expensive purchase, but Tivo does their best not to make you feel stupid for buying it.