This lamp is a good example of how the desire for compact fluorescent lamps to fit into the shades originally designed for use with incandescent lamps without sticking out the end has had an effect on lamp design.  Ever since their invention, designers have continuously been attempting to shrink CFLs to an extent where they can fit into any situation where a GLS lamp would be used.  

The easiest type of CFL to achieve this with is the spiral design, as the tube can be twisted into a far more compact shape than with a linear design, as used here.  It's a very ordinary electronically ballasted CFL, albeit a rather compact one.  Merely one inch longer than a normal PS60 lamp, it is small enough for most applications aside from the very shallowest of shades.

Where this particular lamp is a little unusual is that it features a colour temperature of 4000K, rather than the 2700 or 3000K you're more likely to find in a lamp you buy off the shelf in your local supermarket or DIY store.  Higher colour temperature lamps such as this are readily available online however, suppliers such as BLT Direct are a good place to start looking. 

For a compact 15W lamp this one is pretty bright, warming up pretty quickly, in between 1 and 3 minutes depending on the ambient temperature.  The 4000K colour temp is a bit on the high side for my liking in general lighting applications, but a lot of people do prefer light such as this (many even as high as 5000K) which is distinctly less yellow than that of incandescent light.  I'd describe the light from this lamp as a "pure, cool white," not blueish as things tend to look above this temperature.  It does however do a supreme job of confusing my camera's colour balance - it's too low to use the daylight setting, is nothing light right for the fluorescent setting (everything looks green using it) and obviously it's far too high for the tungsten setting.