People who make the effort and initiative to answer my PMs ASAP are an A+ in my book. I wouldn't have anyone else expect any less of me, either.
I really like it when people respond within 5 minutes, or at least by the time I get back online. I reply to PMs as fast as I can.
Yes. To those people who ignore PMs - what, you think you're better than me? although i know spammers get them to become like that.
Normally I respond as soon as I get them but other times I forget that I have them and I dont reply for hours.
Actually it depends on how busy you are. If you want quick result then immediate response works good. Due to late reply sometimes you have to loose business deal IMO. DON.
For me I hate slow... PC, Applications and Internet Connections. I don't like to wait so I hate delays in replying my PM but still the people that I pm are so busy so there is nothing I can do but wait.