This is an absolute must to any Dream Theater fan. I've seen every officially released Dream Theater DVD, and out of them all, this one is my very favorite.
I got this DVD without having ever heard When Dream and Day Unite (except for a few tracks on some live albums), and I was blown away not only by the performance of the album, but also the extras. I'm a huge fan of Kevin Moore, and the documentary is a big part of what makes this my favorite DVD. Kevin makes the documentary very entertaining to watch, because he's constantly making the band laugh, and he seems like one of the funnest guys you could ever be around. It's also great seeing what the band was like in the old days and I especially liked the parts where it showed Charlie, Mike, and John talk about each other member of the band. There are explanations as to how each of the songs were written, clips of the songs being performed in 1989, and an easter egg that is guaranteed to make you laugh your ass off.
The performance of the actual album is also very good, and the When Dream and Day Reunite CD is a great thing to get if you haven't heard the original album yet. I missed out on some great stuff until I heard this. Only a Matter of Time, The Ones Who Help to Set the Sun, Afterlife, and The Killing Hand have become some of my very favorite songs by the band, and the rest of the album is pretty damn good, too.
The commentary is among the best that the band has done because there's a lot of interesting stuff said about the band in the old days (including the amusing story about how James first heard the band, and how the album was recorded), not to mention how talkative Myung is. If you ever want to hear his voice and know his thoughts about the band, this is the DVD for you.
The biggest highlight of the whole DVD has to be the encore, though. Charlie Dominici joins the band onstage for a great performance of To Live Forever, and yet another former member, Derek Sherinian, joins them onstage for an exceptional performance of Metropolis. With seven members of Dream Theater on stage and a killer extended instrumental section, this is the most amazing performance of Metropolis the band has ever done, and also one of the very best overall performances of their career.
Extremely recommended to any fan of this band.