Apparently, people are getting defective products from this first batch of batteries, but mine works perfectly, and it works with 3rd party accessories like the Energizer Charge Station U (Which it should, but you sometimes never know with products like this)! No overheating or anything when used with the Charge Station. Although it takes a long time to charge, but that was only the first charge, I'll update if it takes a long time for each additional charge.
As far as battery life goes, it certainly lasts like you'd expect a 4000 mah battery to last versus a 1500 mah! This is the battery to get versus Nintendo's 3000 mah battery replacement... Wel, assuming you get a working one.