I have been looking at the JCB one and also the Sonim XP1 which is the same thing without the Lego colour scheme (Sonim make the phone for Messrs Bamford).
The big irritant with me and the reason I still have my old Nokia 6230 is that despite promising to be rugged they all fall down at the first hurdle which is proper waterproofing, which I expect to mean waterproof not shower resistant - being able to drive a truck over it is not much use if it goes pop when you drop it in a puddle (quite likely for anybody driving off road). The reason for this is probably as said above but as I have a RIB, a rugged phone that is not waterproof is F A use to me as I will still have to keep it in an Aquapac as I do at the moment and on the boat it forms part of the safety gear in the event of a breakdown.
Of the ones available, I like the JCB but I need to have the Chicken Song as my ringtone therefore it also falls down on that but the lack of waterproofing is the biggest issue for me. Some of them seem to be waterproof and others not, judging by the reviews.
My current Nokia has been drowned in salt water (yes I forgot the Aquapac that time...) and after being rinsed under a cold tap to get the salt out, and 48 hours on top of the hot water tank with the battery out, it is still going strong so that seems quite rugged to me