Looking at this horse the first thing I notice is her shoulder. It is long and a bit steep and the point of shoulder is low. The humerus lays very flat and the angle at the point of shoulder is less than 90 degrees. Her peak of croup could stand to be a little forward of where it is. She is downhill in build and she has a somewhat prominent looking spine where her withers carry into her back. Does her saddle fit OK? Her neck ties in low to her chest. She is a bit straight through the hocks. Her gaskins are a little light.
She is in good flesh and has a nice expression. Her bone is adequate and her topline is adequate.
What does all this mean in riding her. The shoulder construction says she will have some trouble getting her knees up over fences and folding her front legs will be difficult. This is born out in the OP's avatar (if it is the same horse). The horse has uneven knees and is a bit loose with her lower leg. Knees are not to the horizontal.
Her build also means she will be forehand heavy. It will take a lot of effort to get this horse to round and use herself and she will always be compromised in that regard. She is a great horse to learn from and will make her owner a better trainer and rider. The prominent appearing spine may also be an indication of the difficulty in getting this horse to shift her weight to the rear and round (stretch) her topline).
That being said, she looks the safe and sturdy type who will go miles and teach you a lot. Nice horse.