It has been about a month since I bought a TiVo. Although I missed 1.5 weeks of using it, that is one reason I got it.
So far I have to say it has not affected how I watch TV, but how I live my life. With the season pass option, I no longer need to concern myself with getting home to watch a show, remember to record it ahead of time, or even worry about when a show gets moved around. If I miss a schedule change, TiVo will get it for me. I can even set it to only get new shows. Bonus! This is even better than my VCR since I can have it record 2 shows at the same time.
One other thing I like is how it will fill up the space with recommended programs. This has also changed how handle my entertainment. Many times when I come I would just watch a DVD out of my Netflix or Blockbuster queue. It is better than watching some syndicated show for the 100th time. Instead TiVo gathers up programs that I may like, so I can get some variety. It also records things from off hours. I love that it gets Frasier for me at 11:00 PM when I would never watch it on regular tv.
I still have not gotten used to pausing live TV though.