Plone is a great Web CMS & Sharepoint replacement

Having helped various clients in various industries evaluate CMS tools over the past 10 years, I can say Plone is a select few in the elite tools out there - open source or commercial. The fact that it's open source, so you have the flexibility to make it do the last 10% of the custom things you want it to do, is much of the time why some clients choose Plone over Sharepoint, Vignette, RedDot, etc. The fact that the community is probably the best one out there and makes your life a joy... hard to quantify that one, but it's a great thing - some people's heads explode by the attention and responsiveness of the community - people who do it out of pride, not because they're necessarily being paid to help others get up to speed. Yet this service is almost always superior to paid support from the typical commercial vendors (where your support ticket sits for days or weeks if it isn't a 'production system meltdown' level issue.) This last part isn't just a opinion - for one client we prototyped Plone vs. a tool now owned by Oracle (was owned by BEA), and while I was able to hop on IRC and get support in seconds, it took DAYS to get a response from BEA/Oracle, and the client was already PAYING for that support.

In a nutshell, Plone as a tool, community, and well-run project continues to shine as it has for 10+ years now.