The unit is built very well and although I have only had the pedal a short while, the switch I feel will hold up well. I don't use batteries as I use a power supply, but the battery doors are not the most friendly to use so this is not really a problem for me. Considering it uses 2 9V batteries, if you would have to change them too often, I would worry about it being a bit too delicate and breaking something inside the pedal.
The pedal has 4 different adjustable parameters, but I find that with the EVH button pushed in, it does exactly the sound I want for the rare times I need/want to use a flanger. It's nice to have this button as I can set the controls to something more subtle or wilder than the "Unchained" setting if I might want to use that with the EVH turned off.
The unit, although not true bypass, which is something I look for (or at least a good quality buffer), actually does not seem to colour my tone when off, or at least not too much to put me off keeping it in my signal path which some pedals in the past have. Since there are no other TB flanger which have the MXR flanger sound with all 4 controls, I am glad this is not a problem.
The only feature I would want it to have is a gain control as I find the signal with the flanger on, is lower than without the flanger. It's not a massive difference, but is so close, having the ability to fine tweak the gain would make it near perfect.