I only had two real problems with the series:
- The cool echoing effect was gone from the Visitors' voices.
- Martin/Philip. Unless the look of a Visitor's human disguise is somehow 'tied' to his/her actual reptilian appearance (which is not a bad idea, really), there is no way that anyone could immediately recognize Philip as Martin's twin brother. Any Visitor could be the one under that mask.
I will say this, though. Something that really creeped me out about the series: When the Visitor 'Marta' is framed for Charles' death, and her sentence is to spend the rest of her life...floating through space, locked inside the pod with Charles' corpse.