This subject is one of post in DigitalPoint dot com's forums, wrote by TNX.com. Regarding the pros and cons, this poll is definitely worth checked.
TNX wrote some tips which will help to get number one in Google Search Engine Result Page:
- Don't buy (or sell) sitewide links for serps.
- Don't look for high PR links only
- Control link placement speed
- Control the number of outbound links on your pages and on pages where you place your links
- A link from a relevant website is excellent, but a link from a quality site of other niche or other language can also boost your ranking
- Make links look natural
- Don't do reciprocal link exchange
When it comes to google, everything is blur because nobody knows google's exact formula on SERPS or on anything they control. So Trial and error on any rational advise is a good start.