I bought an iPod video this past January and I love it. The battery life is great - it lasted through a 6+ hour car trip, both ways. I would reccomend a battery pack, though. Watching one or two movies can kill the battery pretty easily. I have a battery pack called TuneJuice (if you google that it should come up), and it's let me watch 3 videos plus listen to music without the iPod dying. It's great. I read somewhere where you can't buy it in stores anymore, but I bought mine at Staples for $20. I've also seen it in airports, so I'm sure you'd be able to find it.
Also, there are free programs on the internet that convert your dvds into a format compatible for iPod videos. I have a mac and use a program called HandBrake, and I've heard that Videora is a good program to use for Windows. It takes a while to convert the dvds, but it's worth not having to buy a movie on iTunes when you already own the dvd.