It is much too soon to say about the veterans of Iraq I and II, of course, but for an interesting read try Stolen Valor by Burkett and Whitley. Among other information in it, it notes that, statistically, the (if I remember the number correctly) 2.6 million Vietnam veterans have a lower rate of homelessness, a higher education level and lower suicide and divorce rates then their Vietnam-era (without in-country service) and non-veteran peers. They do have a higher rate of PTSD than veterans of previous conflicts (the condition wasn't actually recognized until the mid-1970s) but developing research indicates that this is more because WWII and Korea vets concealed these problems than because they didn't have them.