Pros: - works with most point and shoots (at least all I have tried)
- easy way to experiment with of camera flash
- allows to use slave flashes with cameras without hot shoe
- metal thread to mount it on tripods

Cons: - rather poor build quality (some glueing was needed on all units I received)
- don't work with my 450D in pre-flash mode with shutter times shorter than 1/25s
- dont't work with older flashes with high trigger voltages

Other Thoughts: In the end I only use it additionally to my radio triggers.

Bottomline: I would only recomend it if you want to use it with a camera without hot shoe. Otherwise I would buy radio triggers.

Pros: It works. I've set G9 to Manual flash mode, Minimum output (Red-eye reduction is off.) SYK-5 is set to flash (not redeye) mode.
I have a homebrew white plastic diffuser (round 8" food container) rigged in front of flash.
Loverly diffuse light...

Cons: Had to try out various settings on SYK-5, G9 & Vivitar flash, but it wasn't too painful. Occasionally unit does fire off a random flash.

Other Thoughts: Glad I hung on to that old flash. Can't use it on the camera because voltage is too high for digital cam, but works fine with SYK-5.
mounted the whole flash rig on an old tripod I haven't used in years. Neat that the SYK-5 has a nice metal tripod screw socket.

Bottomline: Delighted.

Pros: Confirmed working with my Canon 430EX. The flash can be triggered continuously without turning off and on the flash. That was a problem haunting SYK-3 and most optical triggers on the market today.
Confirmed that even with the delay dial turned down to the lowest level, it's not working with the TTL preflash. According to other reviewers, the preflash will trigger the flash gun, but the delay is too long that it misses the main flash.

Cons: Strangely, even when the red-eye reduction switch is off, the flash trigger behavior is still affected by the delay dial.
If I turned the dial up, there will be longer pause after each flash before you can trigger the next one. If I turned the dial down, the pause (no flash period) is too short to be noticeable).

Other Thoughts: I am confident if you open up the trigger, and replace some resistors (or the trim pot of the delay dial), you can have a shorter delay. That would allow it to work with TTL preflash. However, it's probably not worth the effort, given that you have to buy and DIY mod many SYK-5 modules. SYK-5 is not that cheap.
The alternative is to buy many SYK-3 for normal flashes, and SYK-5 for Canon EX flashes (Damn Canon!), and mount a cheap flash on your canon camera body (Damn Canon again for not allowing manual mode for built-in flash).
I have a cheap flash Quantary Q280AF. I found 2 (10uF and 22uF,200V) capacitors from two failed CFL bulbs. Put them in series, that created a combined capacitor of 6uF and 400V. I put it in the flash to replace the 600uF capacitor.
I left the original capacitor in and only disconnect it as there are enough space for two small capacitors. Now close it up, I have a flash that has tiny output.
This modified flash, mounted on the camera, will work in manual mode and no TTL preflash will happen. It's better than the built-in flash as you only need to trigger it once (than click on FEL and then the real shot). It saves your built-in flash life.

Bottomline: Great product. The seller should focus on the Canon EX flashes as the main selling point.
You can't find cheaper trigger that works with Canon EX flashes (damn Canon again!)

Pros: Easy to set up...well there is no setup really, just insert the flash, and off you go.
The flash sync port is extremely useful. I use mine with the Yinyan BY-28ZP bought from DX. The hot shoe on that flash is a little finicky, so the pc-sync port is really nice to trigger that flash.
The hot shoe works fine with my 430EX.
It's a Seagull - good brand

Cons: Perhaps due to rough handling during shipping, the unit came defective. I could feel there's something loose/springy inside, and it didn't work as described - will only trigger when I tap the outter case.
So I pried open the back cover, and found that one of the leads to the photocell came undone. Nothing a little soldering won't do though.
Does not really work with TTL flash metering, as the first pulse will trigger the slave. In other words, normal mode is too fast for TTL, and redeye mode is too slow for TTL. So you have to use manual flash, which isn't really a problem, because you expect to grab quick snapshots when playing with multiple flashes anyway...there's setup time.

Other Thoughts: I contacted DX reporting the defect, but no one answered. I think DX has out-grew its capacity, and that really compromises high quality customer service it used to have eve a year ago.
Since the redeye function isn't really used for me, I wonder if I should've gotten a cheaper version.

Bottomline: Very nice little flash slave trigger!