I have one - only used it once but it didnt warp and was perfect for a quick simple barby for a family of 4. Was hoping it would not be up to it so I could justify the Weber I have my eye on but its gonna have to wait - OH thinks the fold flat is fine
a few weeks ago asda had the square bbq with side table and on 2 wheels reduced to 10.00 from about 30.00 so i bought one! its really great and a steal at 10.00! only drawback is that the legs dont detach easily for storage so you need somewhere to store it as it is.
we used it on a 1 week camping holiday most nights and it was perfect!
the temperature control is adjusted by moving to the food to the outer edges for cooler or towards the centre and over the coals to increase the heat! there is also a higher shelf for smoking/keeping things warm.
I,ve had a fold flat BBQ for 5 years and it hasnt warped , but I use tin foil to protect the bottom which seems to work. To give a variable heat ,I put the charcoal at one end thus the further away from the coals the cooler .