Dream Theater was the first prog band I've ever listened to. After getting into heavy metal through Iron Maiden back in 2009, I didn't start exploring other genres until 2010. Dream Theater was one of the first bands I've ever checked out that wasn't heavy metal. But since they had metal elements in their music, it was easier for me to relate to and discovering/loving them is a cornerstone in my improvement of musical taste.
I wasn't really astounded by their technicality since I wasn't into the technical side of music back then. Their blend of complexity, power and emotion did it for me and that probably is why I never understood people who called them musical masturbators or pretentious. They're far from it, although they had some pretentious stuff in their career (will talk about this on the respective albums)
When Dream and Day Unite : Being an album that isn't really cared about even by Dream Theater fans, the debut was the last DT album I completely listened to. The compositions are truly awkward. They have technicality and nice melodies, but the arrangements are horrific. Vocalist Charlie Dominici is not that bad in fact he's pretty good but the lyrics sound of place on this album. If it was an instrumental album throughout, it'd work out just fine. The Ytse Jam, instrumental track of the album, sets a great example of it since it's by far the best arranged song on the release. My favorites off the album are that one and Afterlife, The Ones Who Help to Set the Sun is also pretty cool. It lacks a "go-to-song" and overall song quality is pretty low.
Images and Words : Could be my favorite album of all time if it had a better atmosphere as an album. Still, composition wise, my favorite album of all time. No weak song. I used to consider Another Day weak but it has grown on me. Pull Me Under is a fantastic rocker. Its rhythm is incredibly catchy for a progressive song, I find myself tapping my foot in the rhythm of it even when I'm not listening to the song. Another Day is a song that best described as "nice". A bit of fresh air before hitting Take the Time, a truly progressive song with absurd time signatures and various rhythms. Features some tasty Petrucci guitar playing, too. Again a fresh air with ballad Surrounded which is possibly Kevin Moore's greatest work with the band, fabulous keyboard melodies, I think it's safe to say that it's the most atmospheric song on the album, too. Metropolis Part 1 is the ultimate progressive epic like Mosh said. Just a flat out masterpiece by every standard, one of the greatest songs of all time. Under a Glass Moon is a well constructed song a perfect blend of odd rhytmic patterns with nice melodies. Fabulous intro, an amazing build-up to the solo, a great solo and after that comes the best part of the song. Portnoy goes nuts, and around 6th minute, a basic, yet amazingly powerful rhythm part just before the last chorus. Wait for Sleep has the best lyrics on the album a great piano piece by Moore. Learning to Live is the richest song in terms of melodies along with Metropolis, the second part of the song is just fascinating. One of their best, for sure. Just an amazing, amazing album. A great band at their very best.
I'll carry on if I have the time.