As long as you say that you in fact only spent 15 minutes with it when talking about it I guess it's fine.
As far as I'm concerned, my opinion on the headphones I've owned were very different from my first 15-minute-impressions. It takes many hours of serious listening to get to know them well in my opinion.
Classic example - first impressions of the SRH940 (when I first got them) - amazing clarity and detail. Really good sound. Why are these so cheap!
Three weeks later - noticing mid bass hole with a lot of the music I listened to, bass just sounds completely 'off' as a result.
Ended up reselling them after a month.
The major problem on Head-Fi continues to be the number of posters who've never heard a particular headphone, yet still continue to parrot what they've read, and requite it as though they've had personal experience with it themselves. Second biggest issue is the new posters making recommendations to others based on the one or two pieces of gear they own - when they have no experience (or baseline) with alternate gear in the inquiriers budget. Thus the hype machine rolls and gathers momentum .......