So when it comes to digital pianos, the same criteria is used when shopping for one of these instruments. You want to listen to the piano closely to see if you like what you are hearing. Also, look for other things such as a certain"feel" to the keys (light, medium, or heavy), the way they move (quick or stiff), the volume that comes out of the cabinet/speakers (big and full or tinny & weak), the overall quality of tone and the way it sound to you such as the bass response, treble clarity, evenness & smoothness in tone throughout the entire keyboard, progressive weighting of the keys, velocity smoothness, proper pedal movement and damper/sustain reproduction, as well as other technical aspects of the piano. All of this does not include other very popular digital piano features such as USB computer connections, headphone jacks, extra instrument tones and the amount and quality of those instruments, rhythm & drum patterns for timing and play along ability, and other requested functions.
I do all of this because as a professional piano teacher and musician, I want to see people enjoy the piano playing experience like I do. There are no words to express just how important music can become in one's life (in a very personal way) no matter how young or how old you are. I teach kids from 3 years old to 93 yrs old and seeing the smiles on people's faces when they're playing piano and enjoying themselves gives me all the reward I really need. I have years of experience with these instruments to give you the advice you're looking for...at no charge. You can also read my reviews of various new digital pianos on this blog as the list is quite extensive.