Quite possibly at the same screening with you Simon (George Street?) and I enjoyed it quite a lot - saying something given I really disliked the last one (and the three before that), it really is a way to show both how to do a modern Star Wars movie AND how to do a prequel properly.
There's still some pacing issues with it but my only real gripe is it denigrates the first movie.
The long running geek meme of why would the Death Star have an exhaust port, design flaw etc.. is what's been used to create the central storyline here, only, it's not a design flaw, it needs to vent gas into space, so it needs an exhaust port, but it's a tiny exhaust port - they remark on how impossible a shot it is and how the guy using targeting computers fails, impacting on the side, this builds up for Luke using The Force(TM) to shoot his guided missiles (given they make a ninety degree turn) and what an astounding achievement this is, he managed to defeat the enemy against the near impossible odds.
Now, now he just got lucky, made the shot set up by Hannibal. So, like the prequels and the awful sequel, it carries on the tradition of ruining the original movies that bit more.
They need to move away, there's a big and rich universe to set all kinds of stories in, they don't have to carry on flogging the dead horse of the originals and ruining our memory of them with each blow.
The Peter Cushing special effects though are remarkable, I guess we're not far away from seeing any actor from any period appearing in films to come, that could really be something, finally, the Arnie vs Stallone fight scene we've always wanted, back in their '80's looking bodies, and not the spitting image muppets they've aged into..