The pressure of a squirt bottle can make it go all up in the sinuses behind your eyes which is really painful when all you prob want is for it to take the short passage to the other nostril. Happened to me the last time I used it and it hurt for an hour, granted I'm always too lazy to dissolve the salt which apparently makes it hurt less.

I never had that problem with a neti pot since gravity can't apply as much pressure. So you're forced to be patient when it's especially blocked up.