In a nutshell, Google Sheets is an online spreadsheet. Crack that nut open and you'll see that Google Sheets is approachable, inherently collaborative, and extensible in ways that make it a big player in some Low Code workflows. Unless you're a Microsoft Excel power user, you probably wont' skip a beat using Google Sheets for your next spreadsheet project (and you'll probably like it a lot better!).
The great thing about Google Sheets is that it's build with collaboration and interoperability in mind. With everything stored in the cloud, multiple users can be working on a file simultaneously (no more Filename - V6 Final Final.xls). Additionally, Google Sheets has a robust API that thousands of other applications tap into — so you can Creating, Read, Update and Delete Information in your Google Sheet from any number of different tools. There are even several low code site and app builders that allow you to use Google Sheets as your backend database.
For us, the question isn't really Google Sheets vs Excel... the questions is more Google Sheets vs AirTable, Notion, Coda, etc. The later tools are a step closer to a true database though... so if our use case is pretty simple, we'll go Google Sheets all day long. If having some features of a relational database is important, then we're probably looking elsewhere.
We love Google Sheets because it has most of the things we enjoy about Excel - while adding in modern features like a modern intuitive UI, real-time collaboration and extensibility through other app integrations.
The rub against Google Sheets is that you need to be in the Google ecosystem — so if you're at a Microsoft shop or don't like Google, you'll probably want to look elsewhere. Additionally, for those Excel power users, you'll probably be frustrated with the a different experience than you're used to (a Mac vs PC kinda thing...).