What do you like best?
The cloud support for draw.io has to be one of it's best features, if not that, the ability to run the Chrome app locally is the next best.
There are times where I found myself working in the field, with no access to the internet, and I had to draw up diagrams, draw.io made it possible for me to quickly put together a good looking diagram that helped me to plan out my work.
The best thing is probably that it is free to use; no cost at all, unlike most high quality diagram applications available.
What do you dislike?
I'd say the drawbacks of Draw.io rest in some of the interface drawbacks; it is difficult to consistently get a specific style, as the object stroke and fill styling often only remembers the last object, and it's difficult.
If I want to make a change to the colouring halfway through creating a diagram, I often have to go through quite a tedious task and redo much of the diagram.
I also find that it is quite lacking for any wireframe design purposes; the grid snapping is unhelpful in that respect, and the icon libraries do not give you much to work with.
Recommendations to others considering the product
Draw.io is great if you're looking for a tool that's easy to use across multiple platforms and devices.
One of the best things about it is that there is no price gate, you can use draw.io without any cost, for that reason, there is no reason to give it a try.
What business problems are you solving with the product? What benefits have you realized?
I have used Draw.io in many different aspects.
The first was for planning a massive PHP and MySQL system that required creating data associations tables, site map structures, and flow block diagrams; Draw.io made this possible.
The second usage was with lighting design and programming; while managing the lighting at a music festival, I needed to program a MIDI controllers to manage the lighting, and I needed to ensure there was no confusion with my lighting team for using the controllers; so I used Draw.io to mock up a quick diagram of the controllers and indicated what each button controlled.
In both uses, Draw.io made the tasks significantly easier to understand and manage.