I think it's weird, given their description, that they don't have natural armor.
As for the size-and-a-half races... I love them.
Large creatures are usually a problem - you end up either with ones that have huge stat bonuses and a bunch of racial hit dice, and usually unplayable because of the ECL, or pathetic weakling giants like in Arcana Unearthed that don't have the stats to justify their size and aren't worth the trouble of taking the racial levels...
I plan on talking my DM into letting me play a slightly modified half-giant to represent a 7' tall barbarian warrior and have that mean something other than the usual "rewards" of playing someone that size (the reason I never did) - you're no different than a 6' tall 18 STR human, but all enemies pay you more attention, you can't fit into captured armor, no one in the party can carry you if you're knocked unconscious, and you live in fear of rickety bridges...