I've done it. For me, it's much harder to be accurate on the seam allowance. There is a lot of extra thread in the seam allowance, which makes the seam allowance bulkier. Also, you cannot press the seam allowances open if you need to somewhere. And, matching seams is considerably more difficult. I would do it again, but only for a denim or similar type quilt and a pattern with large pieces that did not require matching seams.
I did see a really cute one-layer denim quilt made by serger. The pieces were serged from the front with red wooly nylon thread, and then these seams were sewn down to lie flat. This was really cute, and it's been in the back of my mind to make that quilt someday.