I have a Kickr and I love it. Well, as much as you can love a torture device, I guess.
I bought it when they first came out as it coincided with our move to New England. It ended up being a godsend since the next two winters I was completely stuck inside all of January, February, and most of March. Lots of time to get to know the machine. As much as I hate indoor riding, it has the benefit of specificity. I was able to really focus my training and came out flying in the spring. I've also been able to build on those two winters and have no doubt it is one reason my fitness is where it is currently. (which, btw, is a location where I'll NEVER get on the trainer!!
I found there to be an offset regarding power, around 10-15W, as well as some drift as the machine warmed up. I always went off my PM's power reading, however, and just adjusted the Kickr until it put me where my pm said I should be. Doing it this way, no issues whatsoever. Actually, you shouldn't have any issues regardless, because once you get to know the machine you'll have it dialed in. Listen to your legs, I like to say. Plus, what the wattage says doesn't really matter as long as your training is consistent and you track your own data. That said, I do believe they've eliminated a lot of the variation with the newest firmware.
I know there are tons of programs out there, but frankly I'm a bit old school. Lights off, headphones and heavy metal. I did start watching some movies late last winter during some longer Z2 rides, but I was normally pretty strict about 90min and off the thing. At absolute most, I stretched it out to 2 hrs. Running in Ergo mode, that is a long time and I surmised 2hrs Ergo=2.5-3hrs on the road. That was what my legs told me, anyway.
Before the Kickr, I was using Kreitlers and the E-Motion Inside Ride rollers. Both are wonderful, especially the E-Motion, but I couldn't do hard intervals on them. The Kickr enabled me to do this, plus using Ergo allowed me to work harder than I could otherwise force myself.