I've had mine (KR808 model) for a little over a month, and it has been in constant use. I have had no problems with it at all. The paint is wearing off around some of the edges, but it is no big deal, as mine is black anyway. I don't expect it to last forever, but I feel like I've gotten my money's worth already, just in hassle reduction. I would love to see them build a higher-end model with a metal case, etc. I see that extra syringe and tube assemblies are now available to make switching flavors even easier - gonna have to order a couple of those. I have found that newer CoolCarts from V4L have a battery-end hole that is too small - it makes the draw very hard, which is too bad, as I like the way those cartos perform. But regular old cartos and the V4L Premiums work just fine.
A word of caution - do make use of the nice "on-off" switch that is provided. I had not been very diligent about turning it off before putting it in my pocket, and I recently had a "What's that funky smell" moment - I must've been sitting just right and triggered the switch (it seems to be a 5-way switch, so that is not surprising), and it burned the label right off a carto in my pocket. But no damage to the Wetbox itself - a new carto and it was good to go.