The last time I saw them was in 2009 and I enjoyed the show very much. Yeah, Hetfield's voice isn't what it used to be but the energy and intensity their music has live is still there. In fact, the show I saw in 2009 was the most energetic I saw Metallica play since back when I saw them in 1992 and 1994. I've seen them six times and have never been disappointed in their performances. The only time anything they did live bothered me was on the Reload tour when they played acoustic versions of The Four Horsemen and Last Caress. Now that was more embarrassing to witness then listening to St. Anger. Overall, I think their shows are still great and when they announce the next tour I will go to what ever date is closest to me like I usually do for them.
Maybe i'm biased because they are one of those bands I grew up with and have been a huge part of my life. Or maybe it's because without them there's a very good chance I would have never gotten into metal. All I know is I've yet to witness a bad show from them and will continue to see them live. Even if I do eventually see a bad performance from them, it won't be enough to erase the good ones I've seen and it won't prevent me from going to see them the next time they come around.