The Blog Herald writes a good review of Word Press 1.5 for those thinking of upgrading or swapping over.
‘WP 1.5 builds on 1.2, which in itself was very good, so I’ve got no complaints. The static pages and spam handling abilities are definite positives, and the templating system is particularly useful for new bloggers or bloggers who’d rather not play with script too much. Would I recommend changing from 1.2 to 1.5, yes, but if you’re happy running 1.2 I wouldn’t rush, the new version isn’t an earth shattering change and I’ll personally only be rolling over my other blogs and those I’ve designed for a few others over the coming months, but I’ll add that I’ve got adequate spam protection on the others. If you’re running WordPress 1.2 and are having big problems with spam, make the move quickly. It won’t stop spam altogether, but the built in tools certainly go along way.’