Well, yes of course. Any DT album is pretty great in terms of general music, DT12 was in my top 3 albums of 2013. Heck even WDADU is pretty good prog rock/metal in my book. DT12 isn't bad or mediocre by all means, just "not as good."
Which brings up another point, that it's kind of a shame that whatever DT does now will always be compared to their previous output. I guess that's what an amazing discography does for a band lasting as long as Dream Theater, though.
Yeah, but let's face it, wherever there is greatness, this will always happen. "It's a good Iron Maiden album, but not as good as their stuff in the 80s," "It's a good Pixar movie, but not as good as Toy Story," etc. Honestly, I don't always agree with these things. Frankly, I think Iron Maiden has a few albums recently that are as good as the best stuff they did in the 80s.
But yeah, it would be nice if things could just be judged based on their own merits a little more often.
That being said, DT12's merits are phenomenal. I loved it from the moment I heard it, but the more I hear, the more little nuances I pick up and the more I grow to like it and appreciate it.