I have the Nissin i40 and it is a good performer and excellent value for money. I got it ultra-cheap. Cannot remember the price but one of the Australian online retailers had it for little more than half-price plus shipping.

It isn't perfect. I worry about the strength of the rotating hinge mechanism but it hasn't been an issue and the battery lid is a little fiddly with its complex hinge.

Performance is good, nice and compact, comes with a very well designed case.

If you are after a very compact 4-battery flash with sufficient power for general use and ultra simple controls - hard to beat.