Like I said in the other thread, not everyone gains weight. I gained a little, but it was just that-- a little.
And honestly, they do make a huge difference in terms of cramps and how long your periods last. They also make your periods perfectly regular. It's a slight inconvenience to have to take them every day (I suggest night, because when I got nausea at first it annoyed me when I took 'em in the mornings). I consider it worth it.