I can't say that Mesrine previously have left an unforgettable notion for my part, but it's certainly different on Unidentified. According to the press release the music is heavier, faster, catchier and more brutal than anything the Canadians previously have put out. This fits very well with the impression I have. The music is a mixture of grindcore and death metal. There's noting unheard in this cocktail and Unidentified isn't very different from so much else. Mesrine tend to rely mostly on the grindcore facets, but the meaty and dirty sound has that death metal feel to it.
The same goes for the low and harsh vocals. These compliment the music nicely. Mesrine is pretty good at creating some contrasts in the songs. The Canadians blend both blastbeats and slower things in from time to time and the result is convincing, but some of the songs have a tendency to sound a little too much alike, but overall there's no much to complain about. The first 500 copies of Unidentified contains a bonus CD with Mesrine playing at the Giants of Grind festival, Germany in 2005. Usually I don't care about live CD's at all, but Mesrine sound both heavy and tight. So if you have the opportunity, get the limited edition of the CD.