I wanted to get opinions on the Akismet plug-in. Is it effective against spam? Is it a must for a WP site?
Yes, it is extremely effective but you might create a long queue if a bot gets through. I use a combination of security plugins which you can read about in this recent blog post of mine. I explain, in detail, why I chose these various security plug-ins: Best Must Have WordPress 3 Plugins Hope this helps. If you have any questions, feel free to ask.
A blog has to have some kind of spam protection (My inactive blogs also get hundreds of stupid spam comments every month). Unless the webmaster disables comments, an anti-spam plug-in is a must. As far as I know, Akismet is the best around and so you will have to install it, sooner or later. .