I've had a Swiss Card Lite in my wallet for 5 or 6 years. The battery for the light died long ago and I have not replaced it because I carry a much better flashlight on my key chain anyway. I don't use my Swiss Card very often. I forget it's even there most of the time until I need one of the implements.
I really only use the pen, magnifying glass, and scissors and I like having those items on me when I need them. Those three items are the only reasons it stays in my wallet. The knife blade is kind of flimsy and I've never used it so I can't really comment on its performance. I tried using the four-way screwdriver once but it wasn't suited for the task at hand.
When I first put the Swiss card in my wallet years ago I thought it was too bulky but I left it there anyway and I got used to it pretty quick. Generally speaking, it's a useful tool that I can forget about until I need it.