Watch a couple form videos, that goes a long way in not burning out one area too fast.
This. Rowing is meant to be mainly a leg exercise, but you can burn out fast if you just sit down and start pulling away at it.
In addition, one of the most common mechanical errors with this type equipment is to round the back even when using your legs. The hips should be the hinge point not the spine. Also, anytime you can add pulling or posterior chain exercise to your regimen the outcomes are exponential - posture, balancing out anterior/posterior chain imbalance are positive impacts. That being said...for anyone adding rowing into their cardio routine it is recommended you also stretch your hip flexors. Especially if you are one who sits behind a desk all day. Rowing doesn't help relax hip flexors like other forms of cardio.