I received this light for my Christmas 2009 present. I have used it thoroughly (commuting and mountain biking) since then and I'm pleased to report that the light is still as new. I enjoy going out on bright and early weekends rides, but during winter this was obviously difficult to do with the inferior Cateye lights I owned. I read a few reviews and decided that the Diablo was the light for me. Here are my pro's and con's:
Pro's
:: Decent light spread. The light has a long and wide reach on it for such a small unit. I have found it to be perfect on the roads where it picks out potholes and gives a definite glow in front of your nose. I angle my unit down fractionally on the handlebar to ensure potholes are picked out. The light is also pretty good out on the trail, however I would recommend mounting this light on your helmet and using it as a secondary light.
:: Compact. This is a very compact light considering just how bright it is. I now commute into work and can easily throw the light in my bag just in case I need it. Exposure do sell larger light units which seem equally as good but if you want something small and powerful then go for the Diablo.
:: Battery life. Funnily enough, this is raised as a negative in many of the reviews I have read up about. However, for my particular style of riding I find the battery life to be just fine. Putting it this way, I have never actually ran out of juice. Admittedly the light doesn't last very long when on full beam (just over an hour) but you'll find the medium and even low beam let out enough light and ensure the battery lasts longer. When I'm on the road, I have this light on either low beam or low beam flash. I get through 5 days where the light is on for about 3 hours each day. Even with this in mind the light hasn't actually ran out of juice but I obviously charge it up ready for the next week. Personally that is pretty good going. Also, even after all these months I haven't noticed a reduction in the amount of battery life it can hold.
:: Accessories. The good thing about the Exposure lights are the amount of accessories you can buy to suit your style of riding. You can buy double and triple battery cell packs that plug into the back of the unit. I haven't purchased these, but I have seen them in the shop and noticed that they look pretty small. I have purchased the redeye rear light (which is also great). I haven't noticed any real reduction in battery life with the redeye connected. Another accessory I have purchased is a USB charger which I leave at work just in case I need to charge the light.
:: Well constructed. This light has been with me through muddy trails, heavy rain, frosty mornings and long trips and it still looks brand new. The construction is very sturdy and well thought out.
:: Ease of use. When I got this home, the handlebar mount (which is very well built) was fitted to my bike in seconds. I charged the light up and off I went. The light only takes a few hours to charge and has one button operation. The unit also has written instructions on it telling you how to turn it on and off. Another good feature of the light is that it gives you an indication of burn time on the unit so you never forget and it also has a low battery indicator.
Con's
:: Expensive, however I think it is well worth the money. You need to spend a fair amount in order to get a decent light.
:: Battery life. I can see for some people, this battery life wouldn't suit them. But I'm sure there are other good lights available that will cater for individual needs.
:: It would be great if you could use multiple accessories on the unit. Unfortunately only one can be used at a time. It would be great if you could use an extra battery cell and your rear light for example. I think it would be great if Exposure could consider two ports for their next generation of lights.
Please note that the light comes in a great little presentation box with instructions, handlebar mount and helmet mount. Overall, I'm completely satisfied with my light. I'm really glad I upgraded from battery lights to this unit.