I did Atkins years and years ago (pre-vegetarian). Worked great for me, I actually loved it. My mom did it as well and did fabulous. My transition from Atkins to vegetarian was philosophical, not because that style of eating didn't work. It definitely did work for me.
The one advantage I could point to in Atkins over any other style of eating I ever tried was a pretty fast reduction in appetite, which is certainly helpful right at the beginning of a program. It took longer for my appetite to reduce eating the way I eat now. And I don't do myself any favors in that department when I eat off-plan, there is always a bump up in appetite for me when I eat junk (*sigh*).