It's true that there have been a few threads here from people experiencing mag or screaming problems with their 525's. It's also true that there have been threads here from people regarding problems with reels from every conceivable manufacturer. Personally, I wouldn't really expect the 525 mag/supermag/mag xtra/supermag xtra to have a track record of 100% problem free due to the sheer volume that are sold. I have both an original 525 mag and a supermag which I use weekly and have done for nearly two years. Both reels have performed faultlessly since coming out of the box and both still look like they have just come out of the box too. Questionable build quality? You're joking, they're built like tanks.
I suppose that after reading about problems with ABU 6500's, I could brand them as the worst reel available, but since I have never owned or even tried one, I don't think that would be fair.