I'm seeing that in order to have multiple lines of text that it is recommended to use shift-enter to create a new line in text. However, the enter key itself is not used for anything. Please change or add the capability to add more lines just by pressing the enter key, which is how many products would handle this. It probably be simple as just changing the javascript (I assume you are using) to catch the "enter" key instead of or in addition to the "shift-enter combination.
Reasoning:
Other product do it this way.
This Topic creation tool I'm using to create this request does it this way 
The enter key is not used for another purpose in a text box.
Users will have to be trained to use shift-enter to make good interfaces. Users are a finicky and forgetful bunch and i don't want this to turn into a help-desk ticket generating issue when it does not work as expected.
Again, I'm using enter in this ver textbox to create a new line.