Is the quality worth it? Depends on how good your hearing is and what kind of headphones you have. Personally 228 is the lowest I can put up with, which is OK for being out and about but isn't too great on the stereo at home. In the last year or so, I've been ripping everything at 320AAC and in another year or so, depending on what ever the new iPods are like then, will start ripping in lossless.
It's a trade-off, a personal preference. Rip a couple of your favorite songs at three bitrates 128, 192 and 256 for instance listen to them in the usual setting for you and see what you think. Some people would rather have fewer albums to carry around in higher quality, others have more variety but in lower quality.
The only problem of lower bitrates is if or when you start getting into better quality equipment a year or more down the line, which usually means reripping everything all over again. Good speakers can be mercilessly revealing on anything under 320AAC.