Okay,

here's my question...
on http://www.mysql.com/ there are 2 versions for download... 3.23.48 and 4.0.1....

Now my question is, WHY should I or should I NOT pick 4.0.1?
Has anyone used it before? What's your comment on 4.0? What sites/servers SHOULD have 4.0, and what sites definately not?

Thanks for your input!

Use 3.23 for production sites. 4.0 is not stable yet. But if you develop new application, it might be a good idea to use 4.0 to take advantage of new features it offers. But still it is a good idea to use stable version only for production sites.