My New Guinea Impatiens are coming along and they're showing their first true leaves.
I've also started some Burpee impatiens seeds. But of the 100 New Guinea seeds, so far I have what appear to be 40 viable seedlings. So some simple math - 40% success rate! I will point out that spring planting is a long ways off here in Minnesota. If I achieve 40 transplants by the end of May, I will be happy.
One of the critical factors with impatiens is not to over-water. Just let the growing medium dry out a bit before watering but not to the point that the seedlings topple over. When I water the plants, I spray some water at the edge of each cell and not directly on the seedling.
The Burpee Impatiens are the Walmart variety and I've had pretty successful germination rates with those too.