The UI is well thought-out.
If it's off and you press and hold, it goes OFF --- ON --- STROBE.
If you release it before ON, nothing happens. If you release it between ON and STROBE, it turns on normally. If you release it during STROBE, it turns back off.
If it's on and you press and hold, it goes ON --- OFF --- STROBE.
If you release it before it turns OFF, it goes to the next mode. If you release it while it's OFF, it turns off. If you release it while it's on STROBE, it goes back on.
The timing delays are what I'd expect.
If you're thinking, "What is he talking about, that's the only way to do it" - no. What I'm trying to say is, if it's off and you press and hold, nothing happens for 0.5 seconds until it turns on. They could also make it turn on immediately when you press and hold, but only stay on if you held for at least 0.5 seconds. This way, it would have momentary on, but at the cost of not knowing exactly how long to hold for it to turn on. As it is, it's easier to use, but loses a tactical feature.
Mode memory works perfectly. It's always remembered the mode so far. I even took out the battery for more than 5 minutes and it still came on in 110 lumens, so either it always starts at 110 if you take out the battery or it can remember the mode for more than 5 minutes without battery. This is in contrast to Nitecore torches which some people say have problems remembering the mode. I read of one torch where you had to keep it on for 2 seconds in a mode for it to remember it, I think it was a Nitecore. That seems a bit complicated, maybe that's why people have problems with mode memory.
So in summary - switch a bit insensitive, UI and mode memory perfect.