Cydia 1.1.3 is the current stable build of Cydia. Honestly, I find it really confusing why people try to get builds of Cydia that are not released for their system: there is probably a reason (such as, "this build was tested on a specific version of the firmware for use with a specific jailbreak, and wasn't tested on other devices", or "this build actually has a tradeoff due to introducing some other bug"): when a new build is released, it is released to all users, and at that time you should upgrade. Until then, the answer should be obvious: you should not upgrade.
In this case, Cydia 1.1.4 was released with absinthe for the iPhone 5.0 and 4S jaibreaks, but it was released before any testing was done on it (as a surprise to me: I had just provided the bootstrap one night to the people working on absinthe to test, and woke up the next morning to "jailbreak released"). This version made me very unhappy, and while it fixed a few issues people had, it introduced other ones; it certainly caused irritating and verbose errors to be logged on iOS 4.x. Why anyone would want to upgrade to this release is confusing to me.
Cydia 1.1.5 is a build released with the most recent version of redsn0w, and is used for iOS 5.1. Assuming things go well it might get released generally to all users. If that happens there will be an upgrade in Cydia. There may even be a changelog; although, these usually are too highly technical for users to understand, and so when people should be going "wow, that sounds complex: I should upgrade" they instead go "huh, I don't understand it; doesn't sound useful; I'll just stick with this version". Changelogs for a platform are honestly not something non-developers should be paying attention to (and if you are a developer, the exact changelog is pretty easy to get).