Question: When a person says "it´s all downhill from here", does that mean it gets better or worse? 

Answer: Both.  It depends on the context.  Someone can say, "things are good but only going to go downhill from here" meaning things are going to get worse.  Or they can say "that was easy, and it's only goes downhill from here" meaning things will be easier.
This question from the Yahoo Q&A forum is categorized in the topic: Family & Relationships