It's a really fun way to bring to life all your ideas as a developer and that serves you as a blueprint to your application or database, you dont even need to use the mouse, or install anything, the handfull shortcuts and web applications makes it easier to work anywhere and anytime you want,
Your start with a doble click, and just tab to made another module or ctrl+enter and make a child of that module, that way you can keep up with your brainstorm! No idea will be left behind!
Also you have a LOT, A LOT of space thanks to the resize feature that can ajust the size of your bubbles so you can acomodate as many as you want, so you don't have to worry about runout of space, and you add files a images.
You can use the free version if you just need a few diagrams at a time, and upgrade if you need more.
I can be annoying when you need to move a group of bubbles, because you need to click the select button, then select the bubbles one by one, and that can make you lose some time.
Because all the actions are made with the left click, sometimes when you want to move around the bubbles you activate the bubble's menu, that can be annoying as well.
my only recomendation so far is upgrade the select feature and make the bubbles menu less close to the bubble, sometimes i can't see what i was writen i waste time having to move the bubble or resize.
right now im developing a online store and bubbl.us allow me to visualize the Database structure that i have in my mind, see what works, where the relations must be and what tables i need to separate for better normalization. also it helps me when i take the database structure to the laravel Framework, because i can use the verbosity that is use in the framework, that way i can reduce the time i need in development and start thinking in features for my app