I frequently face this question whether it is a wise decision to use an auto-poster software for posting ads on craigs list.
Well, the auto-posting software will save your time a lot particularly it it has CAPTCHA recognition module. But a software can't solve all the issues related with craigslist posting. You must have enough knowledge of how craig's spam filter works and what the category specific restrictions on craigslist to get success. For example, if you try to use an image while posting in jobs section, no software will help you. Because, image is simply forbidden in jobs section (although it's not mentioned anywhere on craiglist).
Another great issue is IP address. You have to find out an way to change IP address while using the auto-poster. This may be built-in feature of the software or may be done using another program. Remember no software can change IP address itself unless you have a source of different IPs (dynamic IPs). If you are using free web proxies to change IP, auto-poster is of no help for you.
Another point is that setting up everything on an auto-poster initially take significant time. So it will not save your time unless you continue for long time.
On the other hand, advantages are that with auto-posting software you may post at perfect scheduled time & immediate reposting may be done if the ad is flagged by the visitors.
In general use of auto-posters is not suggested and it is against TOS of craigslist.