Hello
I have thought on buying an iPhone 5.
Would that be a bad idea?
Do iPhone 5 still have some bugs and errors or does it run absolutely fine?
Does somebody know or should I buy an iPhone 4S?
"Would that be a bad idea?"
Probably not. It would depend on your situation. If you are using rent money or food money, etc to purchase then it may be a bad idea.
"Do iPhone 5 still have some bugs and errors or does it run absolutely fine?"
Most have never had a problem at all. Like any product, some people have issues; most do not.
"Does somebody know or should I buy an iPhone 4S?"
Buy whichever you prefer. I had an iphone original, 3gs 4s and now have the 5 and have never had an issue with any of them, nor has anyone that I know personally.