I agree. Successful is a long word and The form has been successfully submitted is a bland and formal way of confirming something happened.
However, the idea that a form has been successfully submitted is more reassuring than if it had just been submitted without any other status. It indicates that not only was it sent, but it was also received somewhere. Or at least that's one interpretation of success.
What is success?
The problem is that what is successful in the mind of the developer at the time of writing may not match up with the user's idea of success at the time of completing the form. Does success mean it was sent or that it was received or that it made it's way into a database or does it misleadingly mean nothing at all. Is the success a state of guaranteeing a response or some other action.
That's really why the word successful is wrong - it doesn't explain what success means - despite the sense of optimism conveyed.
Does it work for repetitive situations?
If the user is going to see the confirmation message frequently, the phrase The form has been successfully submitted is going to get pretty boring pretty quickly. Much better to keep it short and sweet. If you can make it work for repetitive situations - it'll work for one off use-cases too.
Keep tone and voice relevant
It's important to keep the copy sensitive to the context of the surrounding tone and voice as well. For example, Thanks for that, job's a gooden might not work on a high stakes financial institution website.
Keep it real
Probably whatever copy you put after a form gets submitted is always going to feel like its a message that gets put up automatically, whether there was any real element of success or not. It may be better to give some brief animated indication that behind the scenes something is working and then to indicate the success graphically with one or two words of confirmation or thanks, and if relevant some expectation of what happens next (although if done right, the user should already have been given some indication of what to expect in terms of action and timing.).
So, thanking the user might be a better way of implicitly indicating the success of submitting a form:
- Thank you
- All done
- Thanks for that. We'll be in touch within 24 hours.
- All done - we copied an email to you as well.
- Thank you. You've been sent a copy of this by email.
- Thanks for that, your feedback is appreciated!
- Thanks. In case you need it, your reference is 123456
- Great, your account is ready to use right away
And finally - don't block the user
But that's not all - those messages are not good enough on their own. It's wrong after submitting the form to be given a message (successful or otherwise) that essentially terminates the user's activity on the site. User's should always be guided on a progressive path, meaning that they don't have to backtrack or start navigating again.
So as important as the positive feedback is, it's equally important to give users options of where to go next now that the 'form' task has been completed. This takes away the weight and responsibility that would otherwise be forced upon a simple message.
Giving the user the next steps prevents them from focusing on the message too much, and they won't hang around wondering about what success means, or about whether it really got received. Instead, with your help, they'll be thinking about what else they might want to do.