First, let me say there are a lot of design features I really like about this pit. Herevis a somewhat dated thread with imbedded links to other discussions for your reading/research pleasure.
It appears there are 3 companies making a variation of the same design, HTB Welding, Custom Pits and Greasyhill. Early models had some pretty serious issues with size of the firebox, intakes and exhaust that lead to difficulties in getting up to temp and aintaining a goid clean fire.
That said,it appears the builders, certainly Custom Pits, have since corrected the shortcomings.
EDIT: Here is a more recent thread about mods to the Greasyhill version of this pit.
Sounds like Fatmike has the most recent experience, I'm happy to hear the issues have been addressed and/or there are mods that will make them good cookers.