My disclaimer is that I credit Metallica for getting me into metal music and they are and maybe always will be in my top 5 bands. I have seen them 5 times: 2003, 2004, 2008, 2009, and 2011. My issue with '03 and '04 was, at least the shows I went to James voice wasn't that good, but I had a good time anyhow.
2008 and 2009 James voice improved and the show in Denver is my top show by them as they played Ride, Memory, Damage, Last Caress and Hit the Lights along with the hits.
2011 was the Big 4 show and that is where things dropped off for me simply because Slayer owned the entire night and Metallica just seemed really old and worn out compared to that.
As for the band members, I think now these days James voice is quite good, Kirk can be killer on the guitar as long as he isn't abusing the shit out of his wah-wah; Rob is quite talented on bass and has done a great job taking in the metallica catalog since they really started pulling from it more starting in '04. Lars....well I have made my peace that he is going to get worse and worse as the years go on; he is had his bright spots but I feel like its a waste of my time to join the "OMG he sux he can't do double bass FAIL" crowd. He is what he is and lucky the majority of Metallica's stuff isn't super complex drum wise.
I hope to see them many times in the future but I won't really go out my way to see them; In '09 was my birthday and my Dad came along and helped pay for the trip; '11 was the Big 4 and that was a special event. But mainly due to limits on money I won't travel to see them unless A) they come to Denver, which won't happen until a new album comes out which looking at updates could be next year or 2019 and B) it's something really special like them playing a classic album in full.
To end my rambling I have enjoyed the times I have seen them, but I know there are other bands that can blow them out of the water in a live setting (Slayer, Iron Maiden come to mind), and I don't really have full faith that their next album (whenever it comes out) will blow me away BUT I will always listen to them and take their music to my grave
09/19- Riot Fest (Slayer, Primus, others)
10/24- King Diamond
11/19- Judas Priest