Don't get me wrong; I like a lot of DT's stuff. But sometimes the overly drawn-out instrumental sections (see The Dark Eternal Night, The Ministry of Lost Souls) drag the song way downhill for me. Symphony X may throw a solo in just because Romeo or Pinnella wants to solo, but everything seems to flow a lot better, and it fits the song. Half the time with DT I get the distinct impression that the solo is there for no other purpose than to show off; key changes are thrown in for the sole purpose of solos in different keys. In the Presence of Enemies pt. 2 is a perfect example - once the instrumental section starts, you've got like 5-7 minutes of wank to navigate through before reaching the melodic ending reprise. Same with The Ministry of Lost Souls... talk about dragging a song downhill!
Of course, you may consider the above opinion completely absurd when I tell you that Train of Thought is my favorite DT album. Who would've thought?!