Everett McKay, Principal of UX Design Edge and former Program Manager at Microsoft:

"I believe the long story of largely irrelevant details is what ruins traditional personas."

"...a traditional persona might be several pages long and give all kinds of personal and professional details"..."Much of that detail will be completely irrelevant to the design problem." 

Instead, McKay advises:

If you do only five things:

1) Keep it simple and focused. Focus the persona on the design task at hand, not the target user’s entire life story. See what you can do with one page and at most two hours, using the facts that you already know. Anything beyond that is detail you won’t need anyway.

2) Make a user model, not a life story. Just give that specific facts to help make good decisions. If there’s not a potential design decision behind the detail, don’t include it. Don’t walk a mile in the person’s shoes. If your persona looks like an online dating profile, you are doing it wrong.

3) Use them when making decisions! If you aren’t actively using your models when making design decisions, you’re doing it wrong. And by “actively using”, I mean applying the model not making arbitrary assertions. Flag assertions that are outside the model and validate them.

4) Train your team to use a simple process. Give some simple training on how to use personas productively. Don’t assume that people will figure it out on their own—my experience shows that they won’t.

5) Be mindful of politics. If you can’t use personas for political reasons, just call them user models. If it helps, consider using the word “agile” somehow. Most likely nobody will catch on.

McKay, E. (2011, June 8). Personas: Dead yet?. [Web blog comment]. Retrieved from http://www.uxdesignedge.com/2011/06/personas-dead-yet/

The User is Always Right: A Practical Guide to Creating and Using Personas for the Web(not in catalog)

   This is a great resource for understanding the differences between qualitative and quantitative personas. Some highlights:

• "Qualitative research is about discovering new things with a small sample size. User interviews and usability testing fall into this category, because they consist of interacting with a small number of users (10-20) to get new ideas or uncover previously unknown issues. Qualitative research doesn't prove anything, since you're talking with a limited number of people, but it's very valuable at uncovereing insights that you can then test or prove."
• "Quantitative research is about testing or proving something with a large sample size... With hundreds or thousands of data points to analyze, you can look for statistically significant trends and be much more certain that your findings accurately reflect reality for all users."
• "Quantitative research us betterat telling you what is happening... and qualitative research is better at telling you why it's happening."

   He also includes some interesting graphs that show what types of information you can get from different sources:

Mulder, Steve,  Ziv Yaar. The User is Always Right: A Practical Guide for Creating and Using Personas for the Web. Pg. 35-54. Berkely, Calif.: New Riders, 2007. Safari Books Online. Web. 6 Feb. 2013.

This article contains through cases where personas were used. It explains what worked and what didn't.