As for Valhalla I do quite like the black boats and darker tone although it would be nice to see Pleasure Beach paint something that isn't grey, black or gold. As for the marketing image, one, the girl looks beyond bored and two, I can imagine this will be as much advertising as it gets. I really do feel that Pleasure Beach need to up their marketing strategies to push new attractions. Alton Towers would have a full blown campaign in the works at the moment.
I agree with you about the lady looking bored. I prefer the original marketing for the Valhalla with the viking skeleton. In terms of a bigger marketing plan, it might depend on what they're doing with it. If most of the work is on things the average guest won't notice (structural work, health and safety changes, lowering the gas consumption etc), then that might be a hard one to base a major marketing campaign on. If there are more things that will improve the guest experience, like better animatronics, or a better sound system, then there's more potential for a marketing campaign.
I suspect part of the reason they're doing the spinning seats on Icon is because they don't feel confident pushing Valhalla too hard. If they thought that the re-imagined Valhalla was going to be a clear improvement over the original (guest experience wise), then I'd expect them to do a big campaign around that, and not be bothering with changing Icon.