Robust build quality, this is where your money goes. Same Steel book shell design as the rest of the Radial pro/j line. This is slightly let down by the steel bolts, which will rust over time given exposure to humidity/salt - these can be replaced with A2 stainless, no biggie.
Sound is great, linear and low THD with plenty of headroom. It excels on sources which need faithful reproduction, this isn't a character DI and it doesn't impart the same sonic signature as the Jensen transformer in the J48 etc.
Great choice for live work, where reliability & transparency is paramount. For studio work where colour is desired, maybe look at alternatives such as the BAE PDI (Carnhill transformer).