An extremely robust database offering that offers superb flexibility in creating a database structure to exactly match your (my) needs even if those are quite complex (as are mine).
Great report writer and, via csv uploads/downloads, great interoperability and portability.
The built-in Apex language and its sandbox and testing requirements are more than my old-fashioned head has been able to wrap itself around and the help documentation is just as complicated. I wish someone would write a simple primer like the many available on the web for say, Python, to help a beginner make sense of how to write say, a trigger or a customised page from scratch and take it all the way through the testing and sandbox stages to the production environment.
Go for it.
What you need: a good knowledge of what your input data is going to be, what reports and analysis you need, what validations are critical, and a decent idea of what constitutes a sensible and efficient database structure. So, yes some prior experience working with databases and tables is helpful, but it's not hard to pick up.
The platform is quite forgiving, so if after creating your database you realise you need something else (or your business needs change), it's quite easy to make changes and retain your data integrity.
The built-in user interface is very powerful even if it's not the prettiest and you get used to it soon. The report writer is outstanding, hiding all the SQL complexity from you and allowing you to create pretty powerful reports using plain English and point-and-click / drag-and-drop techniques.
With a clear understanding of my needs and a decent knowledge of database design I've successfully created an investment and portfolio management app on this platform to meet my needs over the last 6 years. No signs of outgrowing its capabilities and for fiddly stuff there's always csv downloads/uploads and Python offline. Except for a small bit of Apex code and a couple of triggers for one process that I got my son to help me with last year, I put together our entire app purely with point-and-click and no coding.
Using this platform as our backend, we've grown a two-person operation to a two-person operation (yes, just my wife and I) running a business with between 100 to 300 transactions a day for 200+ clients with 2200+ investments in 300-odd mutual fund schemes, scrips and fixed income investments.
And it's available on my iPhone/iPad when I'm out on a client visit - no coding or extra work required from me at all.