Try it if you haven't already by creating a Windows Live account and visiting http://skydrive.live.com and clicking the Create button at the top. You can do Word, OneNote, Excel and PowerPoint.
There are several other Free Software tools that will provide spreadsheet compatibility, Gnumeric being among my favorite. Also the KDE office suite, KOffice.
Can you expand on that? (I work in this space.)
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.
Considering Office costs me less than 10GBP a month over 3 years, and works entirely offline, Google docs doesn't cut it.