I do believe whether Sharepoint will make a big difference to your company's productivity depends on a) what is your level of productivity/integration with existing tools and b) how deeply you use MS technologies.
For example, I work with Fortune 100 companies that use MS Sharepoint + Lync + Outlook rather effectively for collaboration (web based meetings + presence + document sharing + IM + VoIP) --> having attended several multi-site meetings this way, I can confirm they work very well. Its not to say you can't achieve similar stuff with a combination of other 3rd party tools, but if you invest into MS technologies as a whole, these pieces will fall in easier together than trying to stitch them together.
Take my own company as another example: We are an IBM lotus notes shop (now, now, don't judge us...). One of our teams decided to use sharepoint for "knowledgebase" generation, but because the rest of the company was not using MS tools (not counting Office/Win), it soon got relegated to a 'document store' like others have point to above. But because we use IBM products, our IT has actually done a good job integrating our emails with presence+VoIP + mobile messaging + converting customer and contact data as lotus notes databases as well as integrated workflow stuff - performance management etc. So our employees/managers actually get quite a bit done from their notes client. Similarly, customer contracts/NDAs/proposals/presentations/etc are all automatically available for our sales folks to see/review any time via Notes.
There are of course views on bloatware, web based tools etc, but hey this works very well too. So I guess how effective Sharepoint will be for you will depend on how effectively your IT integrates it with other company processes.
my 2 cents, anyway.