Googles ability to copy formulas across cells and automatically adjust them relative to their new postion is weak compared to Excel. Basic patterns work, but if you are doing anything complex, Google just doesn't do it.

Also, Google's formating possiblities are very limited compared to Excels. I run into this limitation frequently.

There are numerous other restraints I come up against with Google Sheets occasionally, but these 2 are the ones I miss almost every time I use it.

I have not spent a lot of time with Excel Live, so I am not sure how well it competes.