I had a Galaxy 580 MDT and loved it. Great performing 580 with non reference power circuitry and cooling solution, and yet was a 2 slot card rather than a 3 slot like many of Asus's cards. It looked great too and I really miss how well it lit up my case in the spot it once resided, but unfortunately I had to upgrade to the newer 600 series.
The 580 MDT was my first Galaxy card and I was quite impressed.
I have purchased several galaxy video cards and found them to be exceptional cards. I have also recommended the Galaxy brand to people who look to me for hardware advice and I have never had a disappointed client. Just a great product.