Isn't the iMac better value in that case? Unwound get s lot more for your money. I'm still torn between the 2...
It really depends if you prefer having the screen etc built in.
I have a nice monitor (that matches my tv, yay! Lol). I already have a apple wireless keyboard (that i use on my pc atm), and i have a razor mamba mouse (which is kickass!).
Also I know apple products are usually great quality. But i just feel the more things built in, the more chance something will go wrong...
Also I havent owned a imac, but i hear upgrading the hdd on those is a nightmare, while on the mini its reasonably simple. I aint sure about the ram situation on imacs, but you cant get much easier on a mac mini!
So yeah, if you havent got a nice screen, keyboard, and mouse already, and you dont plan on upgrading parts in it, then maybe a imac is for you. Beings i have those, the mini is fine for me.
Im also planning on getting a ssd at some point, 1 of the 120gb for around £130. And itll be alot easier task to upgrade on the mini than the imac.
*edit*
I just watched a video of someone upgrading a hdd on a imac. It looked well scary!

yeah, if you are planning on upgrading the hdd at a later date, the imac isnt very friendly lol.
Heres a link
http://www.youtube.com/watch?v=2YsCTNVEYt8 its for a imac 2008 i think. I dunno how different the latest imac is for upgrading.