I found this weekend's episode to be a bit "meh". It was OK, but the whole robots in a spacecraft, who whilst advanced enough to walk around fighting and so forth, couldn't work out that their whole scheme was going to end badly. That was a pretty bad storyline issue. In general they didn't really explain much, and what was explained was excessively implausible. The Robin Hood bit was however quite amusing, if a little strained at time.
I like Capaldi as the Doctor, we've gone away from the sexy Doctor, and a stream of "will they, or won't they?" concerning him and his female companions, towards some more interesting questions about who the Doctor is, and how he thinks. So far it's not been brilliant, but there is always a bit of a slow start with a new Doctor, and not every episode can be outstanding. I'm happy enough with the series so far.