I don't know if it can do something a plug-in can't but I like my DN34 and regret not having bought two when I had the chance.
You will need the manual as there are no presets of any kind but with it it is extremely flexible ie it phases, flanges, does automatic double and triple tracking, various delays and even (very) basic reverb effects. It is also easy to use it as part of a analogue modular synth.
If you go to the link you will see the inside of the mono unit. Those SAD512 delay chips are long out of production but they were also used in a fairly popular vintage stomp box (forgot the make and model) and I've seen people offering £60 each for them. In light of this €150 seems dirt cheap.