I bought four of these for small summer festival use. The lanterns themselves are very well designed and built. The light output and quality is an order above previous budget LED PARs. White light is pure to the edges of the beam, and consistent throughout dimming.
The operating buttons are a little stiff, but that's the price of excellent weather protection. Fortunately I didn't suffer a downpour over this summer, but I've no doubt these will keep the water out as long as they don't end up sitting in it.
The only problem I've had is in relation to the weatherproof connectors used for these. One of the extension cables that I purchased wouldn't mate at one end. The use of non-standard weatherproof connectors adds a degree of additional complexity to rigging, but the connectors are on flying leads out of the casing, so can be changed.
I'm not really in a position to judge lifespan. With the amount of use they've had over one summer I would be bitterly disappointed if I'd had any failure - but I haven't. All LEDs are fully functional - as I would expect.
Overall, I love 'em.