My current internet connection is Vodafone's mobile broadband and it seems to work better than Three's. Unfortunately it is also more expensive. However, there are some technical issues.

I noticed many forums missing photos from their posting. It turned out that Vodafone uses content control which blocks access to the websites. For example flickr.com and imageshack.us are blocked. It is possible to remove this block but the web interface for this tries to send SMS containing password to the client settings. And Mac mobile connect software does not support SMS. So, switch SIM card from the dongle to mobile and back, visit Vodafone store or call their customer service.

Another problem is with those images which are actually visible. Vodafone uses a transparent proxy to downsize image files. The result is rather ugly as the compression is set to maximum. But this case is easier to solve. The latest Windows software has a feature for this so some smart Mac programmers observed what is happening with the network traffic and created a small application to disable compression. It is available at http://aitne.com/, it is donation ware and it works fine.