I suspect you're talking about the Writer's Digest critique article. They have writing instructors who take works in progress, either from writers they're teaching or those who send them in, and then print a critique for educational purposes for the magazine's readers. A friend of mine did this once, with an instructor I know and worked with.
If you're asking, "do they work to get you good feedback?" it depends on who's doing the crit. You get a good critiquer and you'll likely get good advice. I think you can get similar advice from joining a good crit group or posting work in SYW here.
If you're asking "do they help you get published?" I'd have to say probably not. I'd guess that how-to magazines are not high on the reading lists of most agents and editors, as they have so much to read already. Although they would "help" in the sense that anything that helped you improve your work gets you a step closer to selling it.