I am not saying this because I actually like Load and Re-Load (I completely understand why alot of people don't...), but I don't think Metallica have taken too many steps wrong. I do believe they have sold out on another level, contradicting themselves and so forth, but not in their music. They only changed their sound for the Load/Re-Load era, which was supposed to be one double album in the first place. Alot of bands have done experimental albums (Megadeth's "Risk"??). Of course they are going to want to try something different after 15 years of being musicians and writers, and also growing up. I think staying the same just to please fans is a way of selling out, as you know you are going to please, even if it does get a little old (Maiden??). Musicians do owe alot to their fans, but they don't have to answer to them, they are free to experiment however they like.
Since Re-Load, Metallica have put out Garage Inc which I think is a great album of covers, and it is good to see they didn't just pick all typical tracks to cover. I do agree with Trent that it doesn't have the same vibe, but it is still a rocking metal covers album. I also really like the S&M album, as it adds alot of flavour to some of the older tunes (though admittedly it does ruin a few classics at the same time). This goes hand in hand with the 'experimenting' of Load and Re-Load. Metallica wanted to do a show with an orchestra, and they recorded it and released it so that their fans would be able to share the experiance. If they didn't, fans would of complained that they didn't get to hear the result...
Personally, I don't see why most people have lost respect for Metallica over the whole Napster deal. I agree with everything Lars put forward about the situation, and although I DO use mp3's, I only use them for samples, which is how I think they should be used, with the artists permission. When used as samples, mp3s can make the artist money by getting people interested in the band, and potentially buy the album. When mp3s of whole albums are freely distributed, alot of people feel no need to buy the product, robbing the artist of royalties that they deserve.
Ok, now everyone feel free to flame away, I am expecting it.