I assume you are talking about the new production Ithica M-37 Defence Gun, so I don't think the interrupted barrel threads apply to that one. The one thing I'm not crazy about with the new Ithica is the lack of a barrel hanger at the end of the magazine, it looks like something is missing, though whether or not this affects the strength or resilience of the gun remains to be seen. The Defense Gun due to its shorter barrel and 5 shot magazine will be handier than the 590.
The most common 590, which is the 9 shot 20" version, when fully loaded carries up to 19 rounds and equipped with a sling and side saddle and maybe a ventilated hand-guard and a flashlight, is pretty heavy for a gun that by definition should be fast to bring into action. Still, my 590 has never failed to feed or fire despite some pretty hard use over the last 10 years.