Except for very questionable software and services that do remote decoding, there will never be a unencrypted password out on the server - the database is shared for downloading by your computers and devices, but decoded locally on each of them.
What with the advances in cryptanalysis, it is hard to define a password that will be safe within a few years - so using cloud served passwords protected by nothing by a single master password is at least a future risk.
The recommendation when using Keepass with a cloud-served database is to combine as strong a master password as you can memorize with a key file (that is, another Kbit or two of password, beyond the scope you could possibly remember) which is never shared across the cloud. Having to crack both puts the complexity of brute-force attacks into a region where even the NSA would need a couple of decades (if computers continue to grow faster at the current pace) to break that database.
Of course, there is always the risk that the device itself or other software on the device, are compromised, and dump the screen or memory to an intruder while the database is decoded - particularly vulnerable information should always rely on a second layer of security (like two-factor authentication).