When I first saw this, I could only think — wow! Word processing and spreadsheets are classical examples of areas where web applications will never be able to achieve the quality of desktop applications. But Google made a habit out of overthrowing accepted wisdoms and so they’ve gone great lengths to make their spreadsheets web app feel like a desktop application — with success, for most part.
I have to give Google credit for their user interface design again — using the application is very simple and self-explaining. Everything behaves the way you expect it. Most operations I tried are very fast, almost as fast as what we are used from Excel & Co. When I edit a field, its value changes almost immediately and same goes for fields that have formulas depending on it. Merging columns, formatting — fast. Other things like selection are done entirely on the client’s side, so there is no delay at all. Inserting rows or creating a new spreadsheet is relatively slow — those aren’t operations you use all the time however.
All-in-all the functionality isn’t bad. From what I can see the most important features are there, many people don’t need more. It can import and export files from Excel and OpenOffice — good. There is also an export filter for PDF, so you can print your spreadsheets easily. And it has the usual advantages a web application has over a desktop app — your spreadsheets are available from everywhere in the world, and you can share them with other people. You can even have several people edit the spreadsheet at the same time, and I bet Google already found a way to make changes by other people appear in my browser almost instantaneously.
Ok, there are issues of course, this product isn’t even beta after all. Maybe other people will find them because I only noticed one — the context menu. Unfortunately it seems that context menus are a paradigm that only works well in desktop apps. Too many web sites try to block the browser’s context menu, that’s why I have the Firefox setting
dom.event.contextmenu.enabled set to false (and AFAICT Opera already prevents context menu from being captured by default). As the result the standard context menu appeared above Google’s menu until I changed the pref. And then I saw a menu from which three menu points tried to access the clipboard (even IE changed the default settings and doesn’t allow this any more) and the last one does the same as the Delete key.
All this prooves once again quite impressively the point Joel Spolsky made two years ago: Microsoft lost the API war. Even though Microsoft manages to maintain its monopoly on the desktop, even though people still buy Windows and Microsoft Office — the future is the web where Microsoft can’t play its monopoly card. Microsoft is only one of the players and not even the most important one.
Edit: I found links to some similar products, and I tested those briefly: ZohoSheet, iRows, numsum. They might be great programs and each of them certainly has more features than Google. However, I don’t know how it is with you but for me they just don’t feel right.