Spoilers & opinions enclosed!
So the series started off with a crazy bang and it was something that I did not expect at all. I must say, doing that with him right at the beginning was amazingly done and was certainly a step in the right direction. Bringing back River Song also seems promising, especially that heart-to-heart she had with Rory later on in the episode. I think the writers should think of getting her full-time. (Yes, this means getting rid of Amy and Rory, 'boohoo'.)
Everything was going smoothly, but inevitably enough, the episode gradually grinded to a halt. We were lost in this cycle of poor double-entendres, cliched 'standing-around-doing-nothing' shots and RORY. Now, not to be mean to the lovely Arthur Darvill here, but Rory does not 'work.' He never 'worked' in the first place and will continue to not 'work.' Moffat may have been trying to increase his significance in this episode, but that's clearly not working either.
The cliffhanger, however... WOW. I don't often say this, but the cliffhanger was a true cliffhanger, i.e. a surprise. The stark difference between Moffat's work and Davies' work is that Davies' often ended with something obvious (or in some occasions, disappointing) whereas Moffat has never failed to shock, scare etc. I'm sure many viewers expected the Space Man to turn out to be River, or another Doctor, or even those prosthetic - sorry, prospathetic - aliens.
Not a very promising start to the series, but there were enough unanswered questions to keep us propelled to the second episode (The Lodger TARDIS, anyone?!) And the consequences of Amy's hasty actions are too exciting to not think about.