This news item is in Swedish, but here's a short summary: security expert Eugene Kaspersky is worried about security in feature phones, because they're typically not multitasking, so you can't run anti-virus software on them while other apps are running. Smartphones are better off though, because they're pretty much like regular PC:s, with real operating systems, which means virus protection software will work fine.
Doesn't that sound a bit like mr. Kaspersky is biased in favour of platforms that can make him money? If he was really worried about security, I think he'd prefer feature phones, because it's much easier to keep simple systems secure. But of course, if you're doing what companies like Kaspersky Labs do, make money from helping protect buggy systems, you have every reason to want every system in the world to put on as much fat as possible.