Here is my list of reasons for disliking the Java client, just off the top of my head so certainly some are missing:
- The desktop icon doesn't have anti-aliasing.
- Takes longer to open.
- Everything is laggy, unresponsive, and janky.
- Lacks minor nice UI things like highlighting clickable objects when they are moused over (names in user list).
- Have to manually recolor yourself and all your friends in chat.
- Has an annoying dancing ACU GIF.
- UI is inferior in many other ways, takes more clicks/keypresses to do just about everything when compared to python.
- Replay vault is difficult to find so many new players do not realize it even exists.
- Replay vault interface is complex and cumbersome so many do not know how to use it, or if you do it still takes more clicks. The replay vault is critical for player improvement so if new players cannot find and use it they will all suck at the game.
- The notifications are very intrusive so they have to be turned off, which in turn means you cannot see if someone is searching ladder. Even with them enabled it only pops up occasionally. Python is much better since anytime someone is searching it immediately notifies you in an unobtrusive way.
- The Java client uses much more memory and CPU power, to the point it slows down your entire PC.
- Java client doesn't run on 32-bit systems or Windows XP even though the game does.
- Official FAF advice is to close the #aeolus chat tab so it doesn't consume your entire PC, obviously the client is poorly engineered to the extent that it hinders people's FAF experience yet it is made the official client and the only known option for many people.
- Java client has cost FAF a very large amount of developer time for an inferior and unneeded product. Dev power is supposedly scarce around here and this is an egregious waste. The python client could have simply been refactored and improved. Even after several years of work the Java client is not really any better.