You can finetune the model with Textual Inversion. And you don't have the safety mechanism for nudity.
You can hack on it, modify it, integrate it with other code, etc!
Also, of course, it's entirely free. The web version is actually paid, though it's hard to tell because they're not super transparent about the fact that you're steadily eating through a quota of initial tokens.
The online ones are usually bogged down with too much traffic. Locally seems to be much easier/faster