I own two iPods, a 1rst Gen 10 Gb, that I gave to my wife...OK so I own one now, and a second Gen 20 Gb (bought from MacMall for $259 when the new versions came out) I absolutely love them, but would not use them for critical listening.
I think some of you are missing the point. I have 3465 songs for 9.6 days of continuous music on my 20 Gb iPod (I used 192 mbps MP3 until AAC, which I use the same rate for) This thing has saved my sanity more than once on transAtlantic flights!!! No, it's not 'audiophile' gear. The convienence of having so much of my music available is the reason I never travel without it!!! I even carry a current converter with me abroad so I can charge my digital camera and iPod so I never am out of batteries.
As for the batteries lasting, mine are two years old and work fine. Ed is right, you can change the batteries yourself, though I've not done it. I am reminded of how much I love my iPod when I sit next to someone on a plane who has to dig through their bags to find CD's, while sometimes what they are listenming to sounds good to me and I just call the album up and start listening to it right away...no hassels, and seemingly endless music to boot!
This is why I use iPods........as for MAC's, well if you don't know why I use them....