I really like the eliptical trainer. It sort of can simulate jogging, but with no impact. It's easier on the joints, particularly the knees. Plus, if you put headphones with good music on, you can kind of dance (if no one's looking...hee hee).
Elliptical workout is an individual thing although I have seen quite a few conversations occur while two or three people workout on 'em together.
I like them because they condition my body to play racquetball, and I can personally enhance my knowledge by listening to lectures on CD.
The elliptical machine, I believe, is a great machine. For the reasons you mentioned (low impact especially), I recommend to a lot of people to try it who are scared to go running. However, just be sure that you're training at a high enough intensity. It's very easy to enter into la-la land on the elliptical and not exercise at your training heart rate (65-85% of your max). Other than that, the elliptical rocks!
The elliptical machine is one of my favorite - it's like a light jog through the park, but you can make it interesting by peddling backwards. The different levels of steepness work out different parts of the leg and buttocks right?
As you can see from all the 'pro-elliptical' postings, it is pretty universal that the elliptical is one of the most popular pieces of exercise equipment in the gym today (Club Industry Report - 2007). Depending on the brand, the elliptical can offer elevation levels to target a variety of muscle groups (i.e. upper thighs/lower thighs/hips/buttocks) as well as the inclusion of arm movements (i.e. added calorie expenditure). Remember to not limit your movements to the 'forward motion'. Switching halfway through a workout to a 'reverse' mode is not only fun, but can reduce the risks of 'numb feet' (a common complaint of elliptical users).