The only complaint I have with DEF is that I have to clear the trunk area to access the filler under the spare tire. My other complaint is that they don't put a gasket on the tank lid so it inevitable sloshes some out when full, which evaporates and leaves some white residue behind. Not a huge deal, just wipe it down with a wet cloth every once in a while.
On later models they put the filler next to the regular fuel filler opening under the tank flap, which solves all these issues. I have no clue who thought originally that putting it under the boot floor would be a good idea.
Maybe someone on here knows more about the regeneration options for the DPFs??
There are not many options, if at all. DPF regeneration mostly happens automatically, under the control of the ECU, and the driver has generally no influence over it - he can't start it and can't stop it either, other than of course turning the car off or not driving the car.
There are generally three kinds of regenerations: passive, active and emergency. Passive happens when the engine has warmed up so much and you're driving it so intensely, that the exhaust gases burn the soot just by their sheer temperature. This obviously only happens on longer trips and high speed drives on highways. If the amount of soot in the DPF is not getting decimated by this way and is getting too high, the ECU might also start active regeneration, using post-combustion fuel injection which will burn in the DPF. If that's not effective either (because of too short trips) an emergency regeneration might be needed which is initiated by service equipment/personnel, which is similar to active regeneration, but is done regardless of speed, temperature and soot constraints.
These are all the "options" for DPF regeneration, but as said, the driver (without service equipment) can neither initiate nor prevent or stop regeneration manually.