Original Spec for Lotus Notes (1984) [pdf]

That seems common.

As collaborative software, quick way to create databases, documents, forms, wikis etc - it ain't half-bad, especially considering its legacy and customers (large corporations unlikely to purchase any new, "cool" startup-like collaborative spaces).

As an email system (which is what I have to use it as), it leaves much to be desired, including performance.

A well run Notes system was a real pleasure to deal with. I worked for a 300-ish employee company spread over 4 countries and 2 US states around 2001-2004 and we used Notes for all internal document management, email and later even web content management. The thing just quietly kept everything in sync; distributed servers, mobile users and their laptops and traditional desktops, and never lost a byte of it despite flaky VPN connections, ISP service, change conflicts, abusive use cases, multiple Notes client and server versions, etc.

I haven't dealt with any Notes systems in years, but my memories of the one time I did are largely good. The client had its quirks and Lotus could have done themselves a big service if they had adopted more conventional behavior and terminology, but the end user experience -- judging by easy adoption by new employees -- wasn't as bad as is frequently alleged.

I was going to link to IBM Lotus Symphony[1] in response to your question but it turns out it's only tangentially related to Notes, sharing some marketing names and, eventually, included with Notes (version 8 I think).

Symphony was initially proprietary, then freeware and finally, in 2012, turned over to the ASF as a donation. It basically consisted of a typical spreadsheet, word processor, presentation suite all using ODF as a document format.

So, not what I thought I would find but still slightly related to your question...

[1] https://en.wikipedia.org/wiki/IBM_Lotus_Symphony

Before IBM bought it, Lotus was planning on killing the email functions, and just leaving it as a database and application system. IBM was a mixed blessing to the product - they made it large enough to succeed, but also totally messed with its purpose. IBM used it as email first, application server 2nd. That was never its strength. Oddly, IBM has since spent the last 20 years proclaiming it to be more than email, while showing the same old demos of how sales people can live out of their email box. In short, IBM owned it, but never used it or promoted it in a good way.

Believe it or not, it still is a highly functional NoSQL database, with strong security, and can be put behind other web servers... so while it is mostly a dead platform, some folks do still use it. (If you find one of the few people who know how.) But so much crap has been built with it, it has a terrible reputation. Even most of the people still using it are doing so poorly. Most of the people who do know how to use it well have moved on to new technologies, and the folks I know who still use it don't intend to stay with it much longer.

Really it was ahead of its time, but got side-tracked and messed up instead of growing into its full potential.

Notes is a real mixed bag. On the plus side, its open-ended, fully customizable document database is a phenomenally powerful tool for creating information management systems that map very closely to the unique workflows and structures that arise in any business. As an expression of the promise of office automation, it's pretty compelling.

On the other hand, it's the world's worst email & calendar client and much of its bad reputation stems from users having to put up with that when there's really no need for it ever to have been installed. (EDIT: given that, it's interesting to see the prominence that email receives in the design doc. I'd always thought it was a post-Lotus bolt on, but it was a day zero consideration.)

But far, far worse than that is the stuff you don't realize when you embark on the Notes path. It's a very powerful tool, but a dangerous one too: I saw a telecoms company in the late 90s/early 2000s blow up partly because it relied too heavily on a custom Notes solution that became prohibitively expensive to change as the business evolved. Management got hooked on formalizing all their business processes inside Notes, seduced by the promise of total transparency and operational control. The system got big, and Notes scales badly. Reporting runs that took a few minutes with a few hundred attributed documents in 1998 took over four hours by 2000; I helped put in a SQL Server instance to create a relationally structured copy of the unstructured attributed documents to reduce that time, but of course that was more money. The poor chap that owned the company ended up having a stroke and the company was wound down. That's an anecdote, but on the other two occasions I've seen Notes used for its real value (as a document DB with associated processes) it's ended up in a similar, sprawling and unmaintainable end state.

I guess one way to think of it is as a kind of Excel for processes and documents. End users can do things with it very easily - you can set stuff up that exactly reflects the flow of information and control processes unique to a business, and that's a great tool for helping a business mature and control its operational risks - but its limitations and the systemic risk it introduces are not well understood and only become apparent when you've gone too far with it.