I started out on machines but honestly if I knew now what I knew then, I wish I had started out with free weights. In this thread, there is a good article discussing why machines should be avoided:
http://www.3fatchicks.com/forum/showthread.php?t=136376
Here is also a thread about ineffective but common workouts, many of which are based on weight machines:
http://www.3fatchicks.com/forum/showthread.php?t=81247
There is also a sticky to a discussion about machines versus free weights. The first 2 replies are from personal trainers:
http://www.3fatchicks.com/forum/showthread.php?t=60005
Also, in the last few years, the word 'core' has become ingrained into our brains. Part of it comes from the fact that people using machines use muscles in isolation. Using free weights, which you can learn easily, uses multiple muscle groups including your core. Besides that, machines can make your body move in an unnatural manner which can cause injury. There has been some complaints some of the Curves machines for just that reason. I've heard at least a couple people say they had to quit Curves because the machines started causing them injury type pain.
So yes I can understand someone's enthusiasm for machines but just based on what I've read and experienced, I believe free weights are the way to go and much less injury prone.
Also you don't have to be 'hot and heavy' into weight training to use free weights. Beginner and advanced can use them alike. You don't even have to use a barbell, exercises can easily be done with dumbbells. Alternatively at home, resistance bands are also great.