I got a couple to try out and they do work well... I also kind of like the "lava lamp" look a little...
The only BUT I can come up with is because I'm spoiled by the ProTank and Mini Protank's Pyrex tubes... The tubes on the Tumber can be stripped out if you aren't careful with them ( as it is with the Vision Vivi Nova and such just to be fair ). Of course these don't cost as much as the Kanger's either...
Now the
smoktek Aro Pyrex BCC Clearo is pretty nice... It holds about 3.5ml and has a pyrex inner tube. The replaceable heads are similar to ( but not the same and are not interchangeable with ) the Kanger heads. The vape is about the same on either the Tumbler or the Aro Pyrex. Please note there is also an Aro ( by
smoktek ) that isn't pyrex as well and holds about 2ml of juice.