I'm an average web developer. Just want to find out if it's advisable to use CSS frameworks such as the 960 framework. if anyone has, what are the pros and cons of using it. thanks.
It depends on what you will use it for. It will probably speed up your css development if you use it, but you will lose a bit of flexibility.
It is actually the same for all of those 'frameworks', not only for css...
If you decide to work with a css framework, I recommend reading this article
There's two widely adopted options: 960 and blueprint. Both rely on a grid-based layout system. Both include a CSS reset as well.
The advantage here is obviously that you get more a consistent layout across multiple browsers and if you test on Firefox for example you have a better chance that it looks the same on IE. Because these frameworks are grid based, your layout is also a lot cleaner and well-aligned. Both have horizontal alignment but vertical alignment or vertical rhythm is only supported in Blueprint.
The downside is that it may be overkill for your layout. If you want a simple three column layout then you could just go for a CSS reset plus a three column layout template.
Personally I have found that using these frameworks gives me a lot of creative expression and I have done a lot more with my layouts after adopting these frameworks than I ever did before because of cross-browser CSS hackery. I use Blueprint because I find it very intuitive but 960 Grid System has also gotten great reviews.
Yes, as a starting point, provided you're ready to strip out the stuff that's irrelevant to you, and are happy making changes to it. It's a great way to get started on a layout/design, but it's no use if you then write a stylesheet that overrides the rules in the framework's CSS. Be ready to adjust it to suit what you're working on.
As an aside, I quite like bluetrip, which:
combine[s] the best of Blueprint, Tripoli (hence the name), Hartija's print stylesheet, 960.gs's simplicity, and Element's icons