Personally, I really don't care for the 360's Marketplace, though I do like how you can purchase things online and add them to your 360's queue for download when you get home. I just find it a hassle to find things on that marketplace quickly, especially for New Releases. My big complaint about the Wii Shop is that the servers are unbearably slow to load pages and data isn't as well organized as it should be. I do like the PSN Storefront, though. It's pretty quick and easy to find what you're looking for, though like the Wii Shop sometimes pages don't like to load so you have to try them a few times. And yeah, PSN's download speeds are pathetic compared to the 360's.
As for the topic, it's not really a surprise that Nintendo doesn't want to put games on smartphones. Nintendo has made it very clear over the past year that they deal in luxury products, and they feel that products such as cellphone games are destroying the games industry with their cheapness. While that may be a decision that comes back to bite them in the ass sometime down the line, I can't say I disagree with their decision. I like that someone's upholding the traditional handheld gaming market and not following Apple's lead with bite-sized cheap games. I just wish they allowed developers more freedom in putting games like those on their online stores.