I agree that Redis has the rare advantage that one can understand a command at a time, and the cheat sheet is essentially all that is needed to work with it efficiently. Many systems have a documentation that is much more involved, and in this sense Redis is simple.
Still, the reason I find it non simple is that it seems like you (or other contributors) added a random selection of data structures and operations in it. It is difficult to imagine which operations or data structures will be available without consulting the instructions. For instance, there is hyperloglog, but there are no trees or graphs, or sorted maps. And lists have LPUSHX, but no LSETX, nor there is a LLAST operation (I guess it may be for efficiency reasons, but then LINDEX has the same complexity). Sets have SUNION and SUNIONSTORE, but there is no LCONCAT or LCONCATSTORE.
Let me add an example, since I think it highlights the difference in approach we may have. I find the Scala collections very well designed and easy to work with. Each collection has essentially the same (large) set of operations, from `map` and `filter` to more sophisticated ones such as `combinations(n)` or `sliding(len, step)`. Not only that, but usually this operations will preserve the types, whenever possible. This means that, say, `map`ping over a list will produce a list, while `map`ping over a string will produce a string (if the function is char -> char) or a sequence otherwise. Similarly mapping over a bitset will produce a bitset if the function is int -> int, or a set otherwise, since bitsets only represent sets of integers. This allows me to write even very complex algorithms succintly, without needing to consult the API. I find this very simple from the point of view of the user, although the design for writers themselves is pretty complex.
On the other hand, comments such as http://stackoverflow.com/questions/1722726/is-the-scala-2-8-... prove that some other people find it complex and daunting.
In short: I find Redis easy to use (and this is one of the reasons I do use it often!), but not simple in the sense that it is easy to grasp the design.