I may be the only person who ever loved the UFL-2, but then I did dive with the housed FL-36 after which it was a blessed relief ;-) Seriously a lot of the objections are paper based because the numbers of them in the wild are so small. It is great for macro and its problem isn't pure lack of power (on paper it has a GN of 36 when zoomed in) or that recharge time is too slow but that the capacity of 2 AAs to recover from a savage beating for wide angle dies off quite fast. It does all kinds of things other strobes can't and it really can do FP modes.
I'm really interested in the UFL-3 as it looks cheap, simple and like it will last for a long dive. My reading of the manual suggests it can't do FP modes. All it's control is optical and in RC A or B it'll follow your choices set on the camera, and the manual says it won't enjoy Auto or FP. In RC mode strobes are controlled by low power data bursts from the on board flash which is fairly economical. It doesn't do Mimic/Copy cat/S or DS TTL and so for non Olympus cameras you only appear have a manual slave mode - without preflash cancellation - which is a shame as shops hate carrying strobes which are dedicated. It looks quite useful, for Olympus people like me :-)
P.S. I'd add that the UFL-2 wasn't the simple YS clone I always assumed and proved, when I got hold of one, to be a very capable copy cat that has worked with everything I've tried with it without any configuration other than the power switch.