I don't mean to come off sounding like a mouthpiece for Splunk, but Splunk does work with "cloud" data (hurray for buzz words), it is dead simple to use out of the box and recognizes many special fields like timestamps without any configuration (and also provides extensive configurability when needed) and scales like the distributed monster it is, capable of handling 10-15 MB of data / sec. on a single machines and GBs worth of data per day when scaled out across multiple machines.  You should try it before you judge it on hearsay (and I'll maintain that you should also try any Splunk competitor before judging them as well).