We (4 friends and I) have been buying them because the store is local. We have affectionately started calling the owner 'Mr. Chow' (hangover guy).

1 of the first batch of the 5900 60c's I got has gone totally bad. One cell is totally discharged somehow. The other one is starting to puff a tad and won't balance correctly.
None of the others in our group have had any issues yet. The ones I have are 2 mths old now. It's probably my fault they are failing. I need to remember to storage charge them every time, and forget to after using them.

I also have a bunch of Gens Ace 2 cell batteries. They are holding up well after 3 months of the same 'abuse'.