Any other light I have used! At the basic:
-Power Button. Self Explanatory.
-Big arrows going up and down. For a strobe, I would say this is self explanatory as well.
Of course there is more you
could look at and/or access. And then it is just a matter of hitting the function button until
whatever it is you want to change is highlighted. Once highlighted, you use those big arrows up/down to cycle through the options. It all seems fairly straightforward to me.
If all you ever want to do is to turn the light on/off and change power levels, then this is fairly self-explanatory. Of course, if this is all you ever want to do, the Einstein is overkill.
Once you start using the other features, the user interface can become a problem.
Sometimes I use the modeling light for positioning my lights (It's much easier to aim a hair light when the modeling light is on). Once the light is aimed, I may want to turn that modeling light off (It gets very hot when the modeling light is on and you are using a snoot or a grid).
With an Alien Bee, I press one button, and the modeling light goes off. A second button lets me set the modeling light for full power for aiming, or tracking to help pre-visualize.
With the Einstein, I need to press the mode button a few times until the appropriate part of the LCD highlights. If I am not looking at the LCD from the correct angle, this is really easy to miss. Once I am in the correct mode, I then press the UP or DOWN arrow to put the modeling light into the correct mode. I suppose it's pretty self-explanatory which arrow means Full Power, which arrow means Track power, and which arrow means no modeling light. Of course, then I have to press the mode button a few more times to get back to mode you described (up/down buttons affect power level).
If the Einstein is on a stand, and aimed, it isn't always trivial to get my eyes at the correct angle that makes the LCD highlighting easy to see.
To be fair, if I memorize all the various options, I don't need to look at the LCD. I can learn how many presses I need to get to various modes. Having to memorize how many button presses are needed is a symptom of a complicated user interface.
I'm not saying the Einsteins are junk, or that they are unusable. I'm just saying that their user interface isn't as easy to use an Alien Bee. I suspect the lower button count on the Einstein costs less to manufacturer.
By the way, I don't think the Einstein's power button is self explanatory. Many people incorrectly think the power button will turn the unit off. This is not correct, it puts it into standby.