Fifteen construct hit dice! Wooooo!
Unlike their oathbreaker-punishing kin, maruts are Large. They get DR/chaotic, fast healing, and SR, and have a very high strength score (equalling that of balors and surpassing solars), with small to large boosts to other stats (still no constitution, though).
Melee-wise, there's little that should be mentioned aside from these abilities. Fists of Thunder and Lightning is a very interesting ability (with a strength-based DC to boot), but on the whole I suspect four greatsword attacks to be better than two slams.
Maruts also get a ton of SLAs, which are generally more useful than the kolyarut's, including gems such as Dimension Door, True Seeing, and Greater Dispel Magic (all at-will), Circle of Death and Wall of Force (1/day). Mass Inflict Light Wounds has its uses in healing yourself: constructs can still take Tomb-Tainted Soul.
Despite the construct HD, the high strength and strong SLAs make the marut deserving of a +1 LA.