I am a big R4 fan, and an amateur particle physics geek, and Torchwood's OK, I guess, so all-in-all this was quite the three-great-tastes-that-taste-great-toge
Jokes I liked: Welsh ambassador, and Jack's sulkiness at being the PA; reversing the polarity of the proton flow; the CERN lady not knowing WTF Torchwood was just because they're too obscure for her to care about; Ianto trying to make Jack jealous by going on about Oliver's impressive equipment.
The character stuff was great. Lidster essentially had free choice on the thematic side of things, because when it comes down to it you can do whatever you want with aliens from another dimension, and he chose very well indeed. Being post-S2 the death stuff that's always been there in Torchwood thanks to Jack and latterly Owen is even more to the fore in the characterisation than it has been before, and using the aliens to explore it gives all the characters some fantastic moments, and allows the villain to be sympathetic. It's the Buffy monsters-reflect-the-emotional-drama thing that nuWho usually forgets to do the "reflect" part of. Martha's conversations with Jack and Gwen about their survivor's guilt were awesome, particularly the Jack one because it's so rare that Jack gets a chance to talk to someone he doesn't have to be strong for.
I did find myself wondering a bit whether the emotional stuff would have been offputting for people who didn't know Torchwood, but to be honest I think it probably wasn't. You don't need to know that Lisa was half-Cyberconverted, hidden in the basement for ages and eventually eaten by Myfanwy to get that Ianto lost someone called Lisa -- it's right there at the very beginning. You don't need to know that Owen was zombified for a while and is trapped in a nuclear reactor still undead and that Tosh fancied him but nothing ever happened between them before she died too to get that the team has lost some members. You do need to know that Jack is immortal, but it's clearly established in dialogue. I think fandom sometimes has a tendency to assume that people who didn't pick up every nuance didn't get the gist either: the resonance with our knowledge of 1x05 drowns out the resonance with our knowledge of (or ability to imagine) what it's like to lose someone. (This is one of the many reasons I disagree with that Andrew Rilstone post that's doing the rounds atm, but that's by the by.)
And now I shall moan a bit. Sorry.
I sort of wish Andrew Marr hadn't talked to the guy who helped with the science at the beginning, or that I'd downloaded the mp3 to start with and thus not heard it, or something.
Partly because science guy clearly felt duty bound to disclaim that the fact they were putting on this play didn't mean the first LHC paper was going to have Myfanwy on as a co-author (shush, she does so write particle physics stuff; she's got lots of time on her hands down in the Hub) which just reinforced the humourless geek stereotype.
But mainly because it drew my attention to something I can usually ignore, which is that the science fiction in Doctor Who is made by five year old children with glitter and glue. Science guy clearly felt his job was done as soon as the initial (sometimes clunky but mostly done quite entertainingly) exposition about CERN was over and the aliens had appeared, because surely, surely, surely he would have pointed out ways to make the "bad guys have A, we have something that counteracts A, now let us use it" bit just a little bit less nonsensical without actually affecting the progress of the plot at all. Iin particular, I failed to see why a proton/antiproton collision would have been significantly better than a proton/proton one, but that's because really the world "anti" is magic, as shown by Nine in Rose. Also, the play seems to be under the impression that you can see what's going on in real time at a particle accelerator, rather than having to do statistical analysis of bajillions of recorded events to prove that there are significantly more that look like that than you would have expected from random chance if the thing you were looking for didn't exist. And the plot device that it was all on automatic, and the way you just reroute stuff from completely separate experiments. And so on. And the jump from "I read something that said 'God particle' once" to all that guff about the Higgs boson and life ... well, anyway, like I say, glitter and glue.
None of that really affected my enjoyment, though, I just had to remind myself not to worry about it more often than I normally do. But it did lead to one of those things that makes you ask questions that break the format, though, because at the end Jack uses his 51st century knowledge to sort everything out. Now, he's always been presented as aloof and not telling anyone anything, and Torchwood uses advanced alien tech all the time, but he does this in front of the effectively-from-RL scientist and so she presumably has picked up something. And that that would distort the timeline and so on and so forth, and so all the transcendent stuff at the end is horribly undercut for me by the obligatory offscreen retcon that I assume Jack gave her.
And finally: if you're the sort of heathen who doesn't check xkcd first thing every Monday, Wednesday and Friday and so haven't seen it already, today's LHC related strip is superb. I have spent all day doing the second panel at people.