The last month or so I have been using prompt with the "show errors" feature enabled.
It helps in quit a few situations and it performed well.
Observing the part that was highlighted helped me to see a problem before executing the query( like resharper if you use Visual Studio) and thats a real productivity boost. It also made me see why prompt could not provide suggestions with intellisense giving the user a clue as to why the tool behaves a certain way.
A quick win to make it more attractive / less intrusive : only put red squiggles on non whitespace characters. If you have big sql statement it sometimes takes the whole screen with the squiggles.
Example image http://postimg.org/image/ma915t5cx/