I've used both the WS467 toggle switches and the WS12A decora style switches.
Both types have a mushy feel, and often require more than one push to operate. When you're used to quickly hitting a switch when coming into a room, having to stop and press it again is a major annoyance. Also, on the decora style WS12A, always having to push the bottom of the switch is a tough habit to form.
They also both have a slight delay after pushing before the light goes on or off. Not a big deal there, but again, not what you're used to with a conventional switch.
I had a WS467 controlling my pool light, and it was erratic at best from remote control. It worked fine when used directly, but the whole point was not to have to walk all the way to the side yard to turn the light on. Granted, the light is 400w, and the switch is the farthest away from my transceiver, so it was pushing the limits.
I added a coupler / repeater to my system, and things got a little better for the pool light, but it was still annoyingly erratic.
After some research, I've discovered one of the main reasons the X10 switches have reliability problems is the lack of a neutral wire hookup. This means the X10 signal must travel through the load, which in the most common case of a light bulb, presents considerable resistance.
I've switched to another brand of wall switches, that are only slightly more expensive ($20 - $25 each), but are far superior and have much greater capabilities. I won't name the company, but I think I now have a smarter home.
I have a lot of other X10 gear, and to their credit, the X10 brand plug in modules work great. The only failure I've ever had with one was a lamp module that I inadvertently severely overloaded with Christmas lights. All my other lamp and appliance modules have worked flawlessly for years.