I think it would be awesome pre-dive. My biggest complaint about dive computers is having to deal with 1 or 2 buttons to change the nitrox blend, etc. Programming them pre-dive is a pain so I think an intuitive touch screen interface could make that much better.
Underwater I’d have to try it with gloves to see if I liked it; Small screen, thick gloves (7mm), might make it difficult to touch where you wanted if you had to navigate screens, etc. so that is where the buttons may still be a better option.
For warm water dives though it would be the bomb. :-)