I'm excited to see more holistic competition for InVision. This makes it easier and easier to stay within Sketch and not pay the same rate for developers to inspect as designers to create prototypes.
Forthcoming updates seem like they're attacking DSM as well.
Since Invision Studio didn't make a dent, they've started putting all their good features and updates behind enterprise presumably for sustainability. Otherwise, yes, very competitive field.
I use Zeplin and the experience is good... but I think I’d rather pay $0 for this.
Prototyping on Sketch Cloud needs to be better tho.