The only thing I can logically think he means is that, depending on the wiimote's sensitivity, it is incredibly difficult to keep the reticule stable. This is either a good or a bad thing depending on where your skill level is.
My problem with wiimote is that the actual functionality is so varied from game to game that at best it can be called "unreliable." Actually, that's not really wiimote's fault so much as developer's fault.
I've played a sum total of... a half of a FPS... worth anything on Wii... and most of the time, the movement turn around is too slow, or the bounding box is way too large, or the aiming sensitivity is off the fucking charts ridiculous, or some other in-the-way bullshit. The absolute only thing Conduit got right was that it allowed me to fuck with all these options until I found something that approximated decent, and that took me damn near forty minutes of tinkering. And even after that, I had to deal with Conduit's abysmal gunplay and level design... so what was it for?
Which is my real problem with wiimote: for a controller that's supposed to make life easier, the only thing it's reliable at is making life more complicated. Never have I had to think about what the controller is doing more than I do for wiimote. Half the time I'm not even certain it's my fault. I have to worry about too much light, improper sensitivity, sensor bar obstructions, sensor bar placement, and all sorts of other devices that can "interrupt" the device according to Nintendo's own read out.
Number one reason I play games: to lay back and chill out. Number one reason I rarely play Wii games: because they're usually the exact opposite.
That's why I tend to avoid all FPS titles on the platform, aside from their inherent crippled nature due to Wii's horrendous online infrastructure and its limited power ruining level design, physics, A.I. and other such things.