Mainly design problems. Eagletac had a reputation of using customers as beta testers, despite claim having hired beta testers, in a few hours of receiving mine I found at least 5 or 6 problems. It wasn't even friggin watertight, how hard was it to notice that before release? Some screw holes lack o-ring, and some o-ring track are fundamentally flawed and ring tend to pop out than stay in. Then you have the heavy head and heavy body joined by 4 tiny screws that are screwed into aluminum, and I have strong reservations on the strength of this design. Then there's the annoying strobe, many owners glued something in switch track to disable it permanently.
It's bright I'll give you that, but not a company I'd buy from again unless there's an strong price advantage.