What we have gleaned so far is that much of what we thought has been confirmed. We are more sure than ever that Mars had water. Lots of it. It flowed in rivers which poured into oceans. The same scientists who deny a global Flood happened on Earth will say that one happened on Mars.
Liquid water means there had to have been more of an atmosphere than there is on Mars now.
Without air pressure, liquid water cannot exist. The presence of liquid water also shows that Mars once had moderate temperatures. We are also more certain that the rocks we thought came from Mars really did. The chemical content of the rocks the rover is able to analyse comes close to matching the chemical content of the rocks we are finding on Earth that we think came from Mars. The biggest find so far of the Mars orbiter is that Mars has a faint magnetic field.