It just means you haven't played too much crucible.
Many people tell me to screw off when I talk about stats because I [i]only[/i] have 25k kills and a 1.2m medal score, whereas they probably have 100k kills and a 5m medal score. It really doesn't mean much, just shows how much time you've spent slaughtering guardians. That being said, the better you play and more medals you receive, you'll have a higher medal score than someone who has the exact same amount of kills but less medals.
I've been stacking up my phantoms lately, probably have 20-25 of them.
Medal score in general isn't anything more then an indicator of experience in PvP. It's not good or bad. A 250K medal score would indicate that you haven't played PvP a lot, but that doesn't mean you aren't very skilled.
The only thing that could be considered good, is having reached 250K in a small amount of PvP games. That would indicate you play very good, since you got a lot of medals (kill spree's, phantoms, etc) in a small amount of games.