What google is doing is trying to guarantee that their office products are usable beyond just a simple goofy tool that people can use once, and never return to.  They are creating an environment for businesses that will compete directly with Microsoft's .net stuff, and will probably be MS's only real competitor in that area.

This is good for users because it means that companies can write their quick and fun code using something that is platform independent. Eventually, Firefox will include the javascipt engine that they are writing, so you don't have to use chrome to benefit. IE users will probably never benefit directly, but they might find MS will put a lot of work into making sure folks don't leave IE behind, because their favorite web sites run much faster on another browser...who knows.

I think the worries folks are having are reasonable worries for being part of an early beta. If you don't want to jump in before the waters have been tested....you should wait. But, if you want to have a look at something a very forward minded company is pushing, then take a look. Since it's beta, though, be prepared to find some rough edges that might hurt a bit.