Main issues ive heard and tested are the touch screens on both the 845 (
And i dont think its the size of the screen thats the problem, like my sensation is 4.3inch but i can easily type on a wildfire because the screen is alot more responsive and accurate, it just makes it harder when the screen is small and not working properly.
$50 more and you'd get yourself a HTC Wildfire second hand, something like that... to be honest those Vodafone sets are just rubbish, people say good value $150... i think its a waste of money (I have tried them both) they ALL have issues after a short while and they are all just cheap and unresponsive devices. youd be better off getting a Nokia or something with your $150 IMO.
Im all for a cheap little Android phone but like i said if its going to be touch screen at least get one thats easy to use.
Heres one :D
http://www.trademe.co.nz/Mobile-phones/Vodafone/HTC/auction-403466878.htm