In reply to TMM: Yeah, the igniter is pretty poor. If the ceramic insulator (white bit)isn't cracked, you can carefully adjust the spark gap by bending the wire. This usually gets knocked out during transport though.
To replace the igniter, unscrew the burner head and remove the outer panel. The igniter is so prone to damage and moves out of position, I would sack it off and buy some cheapo lighters instead.
Poor boil times:
Most likely low gas pressure (change the cartridge)
Blocked gas jet. Replace jet, or take out cotton wool filter, clean and replace.
Could be a faulty seal? Change o-ring.
Or, check the burner head is complete. My flame spreader (central wire wool mesh) fell out on mine, had this effect.
If you have problems maybe contact the dudes at Lyon, the importer? Despite these problems, I love my Jetboil - great idea, just not brilliantly well made.