"Dream Theater". These two mere words conjure up horrible images, horrible images of nerds with ponytails and neckbeards, wearing black t-shirts with dragons on them, sitting around a table covered in Dungeons and Dragons paraphernalia, Coca Cola, half-eaten pizzas, and listening to "A Change of Seasons" in the background. Depending upon your particular preferences for how you spend your Saturday night, this might sound like heaven or hell, but given that you are almost certainly reading this on the Internet, I'm going to go with "it sounds good".

To be honest, that negative impression that seems to surround the band is probably undeserved. Prog-metal is a very perilous genre to get involved in, because it seems to fall apart much more often than it actually works, and bands who manage to make a career out of it are few and far between. Add into the mixture the band's amazing technical proficiency, their fondness for odd song structures, and the often-overpowering symbolism in their music, and you have a recipe for music that is really awesome, but likely to be shunned even by most metal fans.

And lets be honest, there are a lot of metal fans who are probably going to despise this album. It's heavy, sure, but it emphasises melody and tone over thrashing riffs and pure aggression. There are also a lot of quiet parts, little passages here and there with nothing but synth and maybe some background effects there. Almost a quarter of this album couldn't really even be classed as "metal" at all, which will no doubt purists who want their music to be all aggressive, all the time.

But if it's aggression you want, it's still here. Opening track The Root Of All Evil might start out with a piano and some ambient noise, but it quickly builds up with some riffs that are heavy, if not quite hard enough to knock your teeth out. An extended guitar solo courtesy of John Petrucci materialises exactly when you might expect it to, but it's nonetheless a fine piece of work that suits the song well. Panic Attack is without question a bone thrown to those who prefer their music a little bit heavier than what Dream Theater usually provide, complete with a pounding bassline. It's definitely a good song, but it does seem a little overdone.

Elsewhere, the band concentrates more on the "progressive" part of "progressive metal". The introduction for the title track, for instance, sounds very similar in tone and texture to the introduction to Pink Floyd's Shine On You Crazy Diamond. The band also do their usual experimentation with weird time signatures, which comes off pretty well. Most math rock bands, and even Dream Theater on previous releases, sound a little bit odd, like they're forcing it, when they put their music into a time signature other than 4/4. However, a lot of this album is in 5/4, and rather than sounding forced, it sounds perfectly natural, like 5/4 is a perfectly natural time signature to write rock music in.

Heavy metal purists who insist that 100% of a metal album should be loud and aggressive will hate this album. Indeed, a lot of the time on "Octavarium" the band sounds like they're more of a prog band than a metal band. Fans who insist that a progressive band should change radically on each album probably won't be too impressed either, since there isn't much here that the band hasn't covered before.Still, for those who like their heavy metal with a bit of a space rock edge, this album should do the trick.