The subject of to checklist or not to checklist always generates heated response! Personally I don't fly often enough that I would feel comfortable trying to do it without. The external checks I don't use a checklist for though. Far better to keep your hands and eyes free to check everything over.
Whether or not you use a checklist, it's not going to help anyone if you mutter 'charge' without actually checking you have one. I was taught to touch each item as I went through the list, and check everything's in the green.
The in-flight checks I have memorised. None of them are so complicated that anything is likely to be missed. Especially not if you use common sense - by the time you're holding your PPL in your hand it's obvious what you should check if you have an engine failure.
However it is worth getting a good checklist for whichever aircraft you're flying. I've just done my Cherokee check out, and looked at a few difference checklists until I finally found one I was happy with. Even so, I've added bits and taken out bits so I'm happy with what it says, and that I won't forget anything.