As an avid Lotus Notes fan-boy
I've been a Notes admin for almost 12 years, both in the UK and the US. I started in 1998 on Notes 4.5. I have seen Notes improve dramatically over the years, probably 6.5x series is/was the best. Now I'm currently planning a global migration of 6.5x to 8.5x, and I'm not looking forward to it in the least, simply because Notes 8 has so many issues, mainly centering around Ecllipse. The performance is terrible - at least during the client start-up phase - and there's still bugs in there from 1998. There have been many, many improvements but there's still so much fundamentally wrong.
I think the whole problem is simply IBM trying to make the client look like Outlook. What (most) people don't grasp is that Notes was designed to remove paperwork. The idea was, that if you had an item which required paper flow from one point to another (Purchase Order, for example) then Notes could take that paper and make the process electronic. So therefore, by definition, it can do email. However Notes is -not- an email platform in it's own right, like Exchange. Also it doesn't have the advanced database functionality such as SQL (hence since v6, the tie-in to DB2). So IBM are trying to big-it-up as a viable alternative to Microsoft, which it is, IF the shop buying it has never been hard-core MS before. For companies that are fairly small or medium sized and overhauling their infrastructure, it's a great product.
I've done several Notes --> Exchange migrations and usually every couple of weeks am offered another by a job agency. I think in the past 5 years I've seen one MS --> Notes conversion.
But I will say, I do know of companies that have switched from Exchange to Notes for email because of all the security issues in Exchange (yes MS fan-boys, admit it, there are some) which become non-issues on Notes. For example, a virus physically cannot function in a Notes environment - it just has no mechanisms to run. All that can happen is a user forwards it on to another person manually. None of this copying your entire address book and spamming everyone with the code. It's also an extremely hardened kernel and uptime can be extensive, once the box is configured and run-in.
The author of the article is correct however, IBM really need to shake up the whole perception of the product - everything from name, to web site, to target audience, to roadmap and everything else that goes with it. I love the product, but I am very seriously considering a platform-switch when my current contract is up.