my doctor is not 100% about my BP type, but he believes I'm rapid-cycling and I have mixed episodes. I'm on lamictal (lamotrigine) for hypomania and it does work well to keep mood peaks at the bay.
I'd also call it a subtle drug: almost no side effects and I didn't notice GREAT changes in my moods besides not letting me get hypomaniac (which is already great). I take 50mg daily, which is a low, entry-level dose, and I believe it can't stabilize all "kinds" of mood swings by itself as it did nothing to my impulsive mood or angry peaks, but that's just a suspicion.
I hope I can stick with it as an anti-hypomania medication, because it's cheap and worked! I just feel like I need another mood medication to go with it and my antidepressant, though I really wished my suspicions were wrong. Time will tell.