haha ok it's your opinion that I'm retarded. I have the same opinion of you. But rather than posting an unfunny macro, i'll explain my opinion to you.
Watershed is a decent album. I didn't say I don't like Watershed. Most actually share this opinion; only two or three songs on the album are "very good" (Heir Apparent, Hessian Peel, and, barely, Burden). Coil, Hex Omega, and Porcelain Heart are all quite mediocre by Opeth's standards. I would say that Opeth and Metallica are my two favorite metal bands. Thus I measure them by similar standards. So that's three good songs out of seven for Watershed.
This is where my opinion may be dismissed; the proportion of good songs to shit songs is higher for Death Magnetic than Watershed. I can honestly say I enjoy almost all of the songs on Death Magnetic (except Unforgiven III, Broken Beat & Scarred, The Day That Never Comes). Death Magnetic has better riffs, better structures, and is, generally, a lot more coherent than Watershed. I would even say the solos and lyrics are marginally better on DM, but that's not saying much because the solos and lyrics on both of these albums are pretty much shit (except Mike's solos of course). So seven good songs out of ten for DM.
7/10 > 3/7 = Death Magnetic wins...understand now?