I always pay attention to how the transition to mobile mode is implemented, because that's where all the programmers' flaws most often "come out". If the site adapts smoothly, does not require constant page updates and at the same time retains the full functionality of the support chat and cashier operations, this is a sign of a high development culture. Now many people are switching to progressive web applications that allow you to play even with unstable 4G, and this is a great trend for those who don't like to be tied to their home PC. It's also worth looking at how quickly the real-time winnings on the main page are updated - if the numbers are "live", then the server data exchange is configured perfectly. In general, the modern entertainment industry is becoming more demanding on hardware, so I personally prefer laconic designs without unnecessary garbage, where every megabyte of code works for the result.