I want to start out by saying for the price, you aren't going to beat this machine. I got mine for just shy of $80 and it's definitely worth that.
I'm 5'9" and I weigh 165 pounds, I have a small apartment which was one of my reasons for getting this machine, along with the price. Personally, it's just not enough for me as it's resistance is reliant on a hydraulic piece that once it gets warm, is much too weak for me. My girlfriend is 5'2" and less than 125 pounds, and it's perfect for her. She doesn't have to worry about slamming her knees, and even when it heats up she can put the resistance up to one of the higher settings and it works well for her.
To explain the "warming up" of the hydraulic piece. As you are rowing, it gets warmer and warmer, and the warmer it gets the less resistance you'll have. So after 5 minutes it gets pretty easy, and after 10 minutes you are basically just doing the motions without much resistance. Personally, I wish I ordered a different machine (and wish I kept everything because I would return it). If you are 5"7' or shorter, and if you weigh less than 150 pounds, this might be the perfect apartment-sized rowing machine for you.