The most annoying thing with Calc is inconsistency of key binds among applications. 

 Key bind     Other applications  Calc                  Competitor 
 ===========  ==================  ====================  ====================
 Shift-Enter  a line break        to the previous cell  to the previous cell
 Ctrl-Enter   a page break        a line break          committing a text
 Alt-Enter    no assigned?        committing a text     a line break

When i attempt to insert a line break in a cell with Calc in the same way - 
by pressing a Shift-Enter - as i do with Writer and Impress, i cannot make it. 

Additionally, many users who had tried to migrate from the competitor to Calc 
asked how to insert a line break in a cell with Calc. Some of them probably 
could not find an answer and consequently abandoned their migration due to 
the bad experience. 

Please reconsider of the inconsistency from a User Experience's point of view 
since OOo/SO/SS is the highly integrated, productive office suite.

Thanks in advance.