You’re right, it means that! The problem with expressions, is that they are very hard to translate in English because of the complexity of French!

This expression often implies that I believe that you’ll like it very much – whatever is being referred to (and thus we’ll talk about it again). See for example the Wiktionary in French.

This expression means : “Tell me about it !”. You use it when you want your interlocutor to know how much you find something great.

“Goûte ce vin, tu m’en diras des nouvelles !!!”
means
“taste this vine, believe me, you will find it wonderful !!”