Right a 3G mobile dongle will give speeds of up to 7 mbps and typically between 1 and 2 mbps far faster than the speeds you normally get in cyber cafes that operate off 'landlines' and typically use services that offer maximum speeds of between 512 kbps (more common) and 2 mbps (more expensive so less common) and typically run much slower.
Safaricom has good coverage over most of the country, ask someone where you are going what Safaricom's coverage is like there. Especially if they can get a 3G signal. If they can that is your best solution. A Safaricom 3G dongle costs 1,999 shillings and data bundles are relatively inexpensive. Details on Safaricom's website.
The vast majority of us here in Kenya access the internet via either our phone or with mobile dongles plugged into our computers. I am lucky, where I live I can use HSPA+ which gives a theoretical maximum speed of 21 Mbps and I have clocked it at 14 mbps which is considerably faster than the speeds I was getting using friends' WiFi in the UK, but the service is limited to a few areas