I don't know if this is a problem with the user interface, or if the game always did it, but I have noticed that if you try and look at anything on the Illyriad official website it logs you out of the game. For example, I was trying to look over some of the state tables for the troops in the game that are posted on the website, and every time I opened up the links in another tab it kicked me out of the game. Is it supposed to do that? I guess it might be set up that way for some reason in order to keep people from logging into multiple accounts at one time, but I wasm't on the login screen. Just viewing the game overviews.
I also have gotten error messages in the compose mail screen several times. I am to the point that I don't even type my messages up in the mail screen anymore because they just end up getting deleted somehow halfway through typing em. I just type whatever I am writing up in notepad then copy and paste it into a new message in its entirety. I hate retyping long letters 3 or 4 times cause I lost em. lol.
Also, I have been having trouble with the little green and blue icons that pop up over the icons at the top of the interface indicating you have goods incoming/buildings upgrading/production going on etc. Particularly the icons over the building menu. They virtually never work when I click on them, just act like they are not buttons at all. Sometimes if I log out and back in they will work, but as soon as I so anything like upgrade a building or make some diplos, they stop functioning again.
Also, while I like the interface while using my computer, hover menus do NOT work well on any kind of touchscreen device. I have multiple android tablets plus an android phone, and the game really does not work on any of them, and it is down right dangerous to browse researches on one. I was looking around the game on one of my tablets during my lunch break yesterday and thought I would read up on what some of the different researches do. The research descriptions are accessed on a computer using a hover gesture, by simply pausing the mouse pointer over whichever one you want to view. On a computer this works great. On a touchscreen, there is no hover gesture. Generally, the hover gesture gets converted into a tap gesture on a touchscreen device. Not so for Illyriad, I have discovered. Tapping a research box starts that research if you have enough research points available and space in the research queue. I inadvertently told the game to start a 3 day research that I definitely did not intend to start. Lol. I didn't even know what it was and just wanted to read the description. I definitely won't be making that mistake again!
The gestures could definitely use some reworking for mobile device compatibility.