I spent a long time trying to choose between the PS4, P4 and the S4. I ended up going with the PS4 as I could see myself using both the pliars and the scissors. When it arrived I was struck by the quality and the compact size of it immediately. It lives on my keyring and rarely a day goes by when I don't use it for something.
I've used every tool on it (including the end of the flat phillips driver to tighten my glasses screws) and they are all superb. Other reviews say the bottle opener takes a few bites to get the lid off and that's true, but it's a back up opener to be used when no other option is there so that's not a problem for me. Each tool is well designed and of the highest quality. The pliars are much more powerful than I'd expected and I've used them to cut through small-ish nails. The knife is small but perfect for opening tricky packages on the go.
Overall, a good looking tool that can easily sit on your keyring and packed full of useful features. You'll forget you have it there until you need it. I can't recommend it enough.