Progressive rock and metal attempting to emulate standards of classical music and falling on its face is pretty disappointing to me, and I find that often times such musicians better express themselves in a more modestly expanded upon rock/pop song format,
I actually like hearing musicians try to challenge themselves to write something more complicated even if it doesn't always work. I hate when a song is more 'pop', I don't like the feeling that I am listening to something intentionally toned down because the musician is inept to play anything or even try anything better.
At the same time people like Yngwie Malmsteem annoy the [censored] out of me because they are trying to be too technical and sound like [censored] which Yngwie does most of the time. I love guitar shredding or whatever you want to call it but like a poster above me said it lacks emotion, it's technical for the sake of being technical..... I guess I'm hard to please

That being said I do love just straight forward traditional metal, Judas Priest, Saxon and Accept for example. I actually bought Accept's Blood of the Nations and Saxon's Into the Labyrinth over the week end and they are fantastic, which I may as well share. The Accept song has a nice guitar solo, it isn't hugely technincal but to me has emotion and gets it's meassage across very nicely, imo:
http://www.youtube.com/watch?v=RUkGbOmJz8I - Saxon
http://www.youtube.com/watch?v=z45SckM3k3A&feature=related - Accept (This is a ballad, beware)
http://www.youtube.com/watch?v=VFwGwVN_AOM&feature=related - Accept (For those that dislike ballads a more "balls to the wall" song)
As for Dream Theatre I find them mind numbing, though there is much worse stuff...
.... the only thing off the top of my head that I can think of that I like Dream Theatre related is a solo song by John Petrucci http://www.youtube.com/watch?v=cVkSF32kK9w , whih I may as well share here also