At the end of the day, anything with software related projects can and often does get delayed.
From my understanding the flywize issues at United, have been primarily related to UALs desire to do extreme development and customization of the flywize platform in an effort for it to take over other non flight planning functions that its current legacy systems perform. In otherwords, the UA flywize version looks and will function very different from its contemporary version at other airlines.
For an idea for project debacles look at Lido instead and its experience at place like Qantas following years development and millions of AUD sunk to have the plug pulled, or more recently at Frontier where after three abortive attempts to go live, the project now sits frozen!