Pros-
Really easy to install, and the fixture holds nice and tight without slipping. The light has a small amount of play to allow you to angle it away from oncoming cars which is a bonus.
Multiple levels of intensity gives great versatility - at 400 lumens I can still see enough even on completely unlit stretches. 1100 lumens is great when I get off the road and could do with being able to see more of my surroundings. Two different flashing patterns are great for added visibility during the day.
Seems to be really well-built, and has a "premium" feel. Has survived a couple of moderate showers, though it hasn't yet been tested in prolonged heavy rain.
Cons-
Bit on the pricey side, though as I said it does feel like a premium product, and I don't feel ripped off after spending £60-ish on the set.
Battery life feels a little stingy. I'm lucky that I only have to use it for 30 mins at a time in the early hours so I only need to give it a top-up every other day. Worst case for me is that after about three days of this sort of use it went into the red. I could see it being a pain if you needed to charge from empty every day though.
No way to change intensity down, you have to cycle through brightness levels in order. This is only a minor thing but if I want to step down a level (say from 1100 to 800) I have to make four clicks, which means scrolling through the two low-power flashing settings, and that's not ideal on the move in the dark.
All in all though, I highly recommend this light. I'll definitely look to Cateye when I get round to buying a backup light, and I would definitely buy another one of these as my daily driver if mine got lost or broken.