I have a confession to make: I've never knit a sweater flat. The first sleeveless top that I made was in the round, and ever since I've never seen a compelling reason not to knit all of my sweaters that way. Oh, I certainly knit certain parts flat and sew them together, but with every sweater I've made there's always been an "in the round" component (whether it was written into the pattern or not). I see the benefits of circular construction to be numerous: For one, seeing it in "body form" helps me visualize if it looks the right size, and if I still have doubts, I can try it on. For two, I personally hate knitting flat. It's not that I dislike purling, it's all the turning back and forth. It breaks my rhythm, and I always end up with my yarn and needles a tangled mess. And finally, knitting in the round means I have that much less finishing work to do when I bind off the last stitch.