It crashes in call (total power off); data availability hasn't been stable (I would say about once a week I have significant issues where I won't be able to use email, a browser, etc. for the entire day); maps/GPS is iffy; I think there are some interface design flaws.*
I used to have an iPhone 3G. I thought it was great.
I switched to VM for the plan -- $25/month for 300 minutes, unlimited text and data ($40/month for 1200 minutes).
Honestly, though, these problems haven't really bothered me too much. I've found that for $25 or $40 a month it's fine with me if the experience isn't "perfect".
*My friend also experiences these same problems
Search #vmdd (Virgin Mobile Data Down) on Twitter and follow the fun.
The Optimus V is a late 2010 phone. My iPhone 3G is from 2008 and hasn't been sold by Apple for a full generation. Your comparison doesn't really make sense.