Its not the idea that cell phone, water proofing or solar charging hasn't existed prior. Its that a company blended into a small form factor without involving accessories that need to be carried around or cases that need to be applied which often hamper the original function.
Doing this makes it far more likely to actually be used.
The simple point that they achieved an efficient enough standby mode that it gains battery power while on in the sun despite such a small amount of surface available is impressive.
Of course...if its other characteristics are not up to par or its price is massive, or if the solar cell array has a short lifespan/low durability then everything becomes moot. Still its a nice step in a good direction.
Would make sense to get a clear pocket that clips to belt, brief, backpack, armband etc. to keep it in the sun when out and about thus maximizing exposure I would imagine.