Hey there you loud guy.
It works great over 3g and Wi-Fi using Sprints EVO. I am not in a 4G area but can only guess that it would be comparable to Wi-Fi. You have to get the app for adroid that is available in the app store. $30 frog skins may seem like alot but, it is worth it. After getting my EVO I tried the ORBLive app (which is $10) but, after trying to get ORB to work and fighting with it for the last 6 years, I give up.
I purchased the SOLO only after I learned there was an app for the EVO. The experience is much better than anything ORB has ever delivered to me, and I liked ORB.
So, the TIP of the day is , just buy the app. As long as you have 3G going to the EVO, you should have decent to excellent results. Since Sprint is charging us an extra $10 a month, you might as well use it. This is one excellent way to do just that. I have been very happy with combination so far, and it can only get better.
Hope this helps.