The method you use of exercising obviously depends upon your goal. People usually either want to lose weight and tone up or build muscle. But there is a method of exercise that has a place in both of these goals.
The rowing machine is a wonderful invention that in the opinion of many is second only to swimming for an all out body workout. I've known many people in the gym who can run for 30 minutes on a treadmill almost without breaking a sweat but these same people can't last 10 minutes on a rower. This is because the body mechanism involved with using a rowing machine triggers the whole body to move to reach the goal. The compression and release is similar in effect as the infamous burpee. Google 'burpee exercise' to find more information about this form of exercise favoured by prison inmates.
The cardiovascular effect of using a rowing machine is dramatic to say the least. Your lungs, heart and virtually every muscle fibre in your body is made to work. Correct breathing during the exercise routing is essential and will accelerate the speed at which you burn calories.
Another benefit of using a rowing machine is the low impact it has on your body. With a treadmill for instance, the pressure placed on the knee and hip joints can be excessive especially without the correct footwear. The rowing machine on the other hand involves sitting down and the movement is a flowing motion with no jarring of the bones and joints. That is not to say that correct form isn't important. Using a rowing machine incorrectly can lead to back and hip problems. Make sure you view some videos that are available on the internet which illustrate the correct way to set up and use a rowing machine.
Many rowing machines are also very easy to store, unlike a treadmill or other type of fitness equipment. The cheaper type of rowing machine are not usually foldable and neither are the high end rowing machines. But if space is limited in your home there are some reasonably priced rowing machines that can be folded away for easy storage although this does tend to promote forgetfulness and the 'out of sight out of mind' apathy that is prevalent in society and should be avoided.
Rowing machines vary greatly in price from around $60 at the very low end of rowing machine (not recommended) up to $2000 for a professional piece of fitness equipment. For the beginner I would recommend looking at around the $300 range for a rowing machine that may not have all the bells and whistles of the top models but should be sturdy and well made enough to not cause you an injury and should last you for many years if you look after it. Keep it away from damp conditions and dry off the sweat after use to prevent rusting of any metal parts. Look after your rowing machine and it will look after you.
If you are looking for an enjoyable way to get your body in shape then many people would recommend rowing machines as their ideal choice of exercise equipment.