To be quite honest... I havent seen a more unrealiable site than WU - considering its size and popularity. Look at other this popular sites, they do go down, but only very occasionally, for a much shorter period and most importantly - even if it was say DDOS attack, which is hard to prevent, then what disappointed me (but not surprised me) was that if you looked at other communication channels they have - i.e. twitter, fb etc. - even several hours after they went down there was not a single post about what is going on (but lot of people asking). This really should not happen and it is on average I would say at least once a month.
