That you could easily hire a skilled writer to create a conversational agent in this because little coding knowledge is needed to do it correctly. It's also very visual and easy to make sense of the flows because of that. Their help team is also fantastic. Web widgets, Facebook, and more are all inherent to the app, so non-developer writers will have an easy time of making a bot happen.
Tutorials for the product are a little sparse (though their help team is great, so that makes up for it), and their API.ai/Dialogflow connecter is in Beta, so there are still little idiosyncrasies with that. It's still far superior to an NLP alone.
Ever written dialogue trees in Visio? I have. Expect a similar creative experience, flow-chart style, with easier transfer of text and integrated stock code for things like web widgets, We Chat, Facebook, Twitter, and so on. No code needed to call up other flows or integrate NLP, but you will have to hook in an NLP API to make that work. Thankfully, Reply has its own (currently Beta) webhook for Dialogflow (formerly API.ai). It comes with other stock integrations like that, but I haven't used any of the others. You can also create your own hooks to integrate it into your app seamlessly.
Writing-wise, it allows for visuals like images, GIFs, and emojis for better chat communication.
Best practices writing-wise that we've nailed down so far are typical short nodes with options to interact as frequently as possible (so, standard convo agent rules) using plenty of emoji visuals to offer "emotional" context for the user. If it's meant for customer service, you have the option to use buttons instead of quick replies to offer links as part of the button options.
Overall, it's a GREAT tool for your straight-up writers for little to no technical experience, but if you want the most out of it, you'll need to get a creative technical writer (with coding background) to effectively implement NLP as a part of the process.
Happy bot parenting, folks!
(Note: Pricing and terms are not included in my review since my company is handling that part. For context, I'm a creative technical writer with coding background who is leading the tech side for two non-tech authors.)