I had to take a drive yesterday, so I popped in "Technophobia", the first of TDA series 1. (Despite the fact that it was casting from my phone to my car system over Bluetooth, I still use the phrase "popped in".) It's been long enough since I've heard it that though I remembered the conflict in the story, I didn't remember the antagonists, how their evil plan worked, nor how the Doctor saved the day.
The thing that struck me about the re-listen is its inherent energy. I haven't figured out if it's the writing or the performance, but though this doesn't rank among the best DW episodes or BF audios (I liked it and originally gave it a 7/10, but it's no "Peri and the Piscon Paradox"), it's exciting and fun. The dialogue is fast-paced, giving the Doctor plenty of technobabble rants, excited ramblings, and excruciating bouts of suffering and Donna lots of sarcasm and empathy. DT and CT sounded like they were having fun first and that acting and doing their jobs were secondary - but is it because the material was good? I'm not sure.
I immediately contrasted this to the series 2 TDAs, and there was none of that. Compared to his performance in series 1, DT was positively uninteresting - but is this because he simply didn't make the effort or because the material didn't give him opportunity? I don't know. I'm just hoping that series 3, whenever it might happen, recaptures the spirit of series 1.