Power Apps

It well suits for some kind of internal process tracking, automation and other works. We can simply integrate, automate, analyze and display. Its low-code solution and rapid development option suits well for internal purpose even a beginner can create app with Power Apps. In out organization we used it for employeeperformance tracking and it currently works well.
I don't recommend it for ui that requires highly attractive design and more complex ui controls. And other is applications using high data transaction and advanced data processing.

Power apps are highly recommended for developing basic web applications as the learning curve is shorter. All resources to build a web app are available online, and the cost of development is almost 0 as the license comes bundled with Microsoft 365. unless the paid connectors are used, a web app can be easily developed with a very low budget.

It's so good as powerful line-of-business applications, I can't recommend it enough. The ability to tap into the Common Data Service and use this information along with custom entities, forms, and views, makes model-driven PowerApps incredibly useful and powerful. It's also very friendly for those who have implement business processes and logic but don't have experience with an actual coding language. There is so much flexibility with PowerApps.

But again, you may have to invest some time figuring out the functionality. Even though there isn't a specific code involved doesn't mean that the work will be simple and quick. You can do a lot with PowerApps, but it might take some time and effort to get a broad understanding of all that it is capable of.

PowerApps is well suited for "quick-wins" and fast prototypes of business solutions. It also is beneficial for situations where business partners and developers work together - it allows the business folks to provide a "quick-and-dirty" prototype which is then fleshed-out by developers that are trained experts on the platform. The interactive and easy to understand representation of the solution allows business partners to "see" the solution and add, remove, or correct aspects of it themselves. It provides a common view and understanding of the actual solution across business units and tech teams.

PowerApps, being a low-code\no-code platform is not well suited for business processes that require many complex computations or large amounts of custom code - such as solutions that are better architected as Web Site or "full-blown" desktop solutions. There are solutions that are just not easy or quick to accomplish in a low-code\no-code platform. Enterprise Architects should know the difference, however business partners often try to create a solution and only when stuck because it becomes too complex do they engage a tech team for assistance - at which point there are sunk-costs involved and hinderences to re-platforming the solution.

Power-Apps can be used for virtually any type of situation. I've seen it used for an office reservation tool, especially during COVID, where that has been extremely useful. I currently use it a lot for various quality assurance forms for various teams who need different things to review for each team that calculates scores, as well as sends the information I need from various sources to SharePoint for analysis later. People can use it for mobile apps or canvas apps - I prefer canvas apps, but you can really create pretty much whatever you want and there are so many different tools and items to use for each app (scanner, signature insert, etc.). So really the sky is the limit.