Used to have one in my Walk Thru when i first bought it, really kept the vsn warm, but can be quite messy aswell as taking up a bit of room (depending on how much you use it...).
In the end I took it out and installed a diesel fuelled water heater by Webasto, which works like a boiler (and also warms your engine up).
But if you're getting a burner have a look at this: http://www.windysmithy.co.uk/
who were recommended to me and also this:
http://cgi.ebay.co.uk/Gas-bottle-woodburner_W0QQitemZ180218947360QQihZ008QQcategoryZ41987QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
and this:
http://cgi.ebay.co.uk/woodburning-stove-woodburner-for-workshop-V-G-C_W0QQitemZ230226825093QQihZ013QQcategoryZ41987QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
for cheaper options.
Usually another gas bottle one on ebay, but not there at the moment.