On the other end of the scale...
I have this:
http://www.justtools.com.au/prod2084.htm - weller butane soldering iron.
Pros:
- sitting on the roof and a wire breaks? that's ok, there's a soldering iron in your pocket ready to go, just light it up and go for it. No power cords, very fast heat up time. **Just don't put it back in your pocket when you're done...**
- Sitting in the garden testing a board but find a broken join? - yeah, you get the idea. handy dandy solder.
- need to solder a wire inside a box? short tool, no wires, very easy to manouver.
- can be used as a great heat gun (red hot iron vent near the tip releases impressive amounts of hot air, which works wonderfully on heatshrink). No need to carry both tools.
- who doesn't want a portable blow torch?
Cons:
- doing a long stretch of soldering? don't forget to break it up with time to refill the iron with butane every few hours.
- butane is probably not good for you.
- temperature variation is a little tricky to control, there is a dial but I have no idea what it equates to - just turn it up/down until it seems to melt the solder/heat the component fast enough.
- doesn't come with a stand, does tend to accidentally get turned of if you push it into a standard holder too fast.
- has a burning hot red iron on the side... right about where your face would be if you wanted to lean over and look right in close at what you're working on. This can get to be kind of uncomfortable, especially the hot air when it reaches your eyes...
- see that lid it comes with? well, you'd be forgiven for thinking that it would be a lid to put on the iron to protect the tip... but it's not. It doesn't fit unless you remove the tip.
- want a fine point tip? or a thicker tip? there isn't much of a range, and the default is pretty big. No SMD for this tip.
All in all it is pretty useful, especially for christmas lights once they are installed in awkward places, but I would probably go for this as a second tool once you already had a nice temperature controlled stable iron for bigger projects.