It's hell of alot better than working as a private office associate. At least with DSOs, you can get your reps and speed in. DSOs tend to be more forgiving of "newbie" mistakes; whereas, private offices have a reputation to protect. Also, staff will never work hard for a private office associate; they will always give away the high prodn cases to the owner (i.e. person signing their paycheques). It's been my experience that corporations don't do this and it's not surprising why more and more dentists are moving towards corporation these days.
However, not all DSOs are the same though. I live in Canada and I think corporations here are largely different than in the States. Not like Aspen Dental where they pressure you crazy on production numbers. I could never work for a coporation like that. But then again, if you're under-producing at a private office, the owner will get rid of you.