Visual consistency is a huge issue with cross-platform (or you may say Transmedia) design on projects. Either clients don't care or designers are forced to fit a website peg into a mobile hole. Jakob chucks his 2 cents into the ring on Transmedia User Experience.
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Via Useit.com
Summary:
Mobile use will rise, but desktop computers will remain important, forcing companies to design for multiple platforms, requiring continuity in visual design, features, user data, and tone of voice.
To conclude:
Cross-platform UIs should be different but similar.
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