Checked it out this morning, it's actually pretty nice!
There seemed to be two kinds of offerings, ones that catered more to the nostalgic idea of marimekko and one that was very contemporary (these weren't so nice). If you like marimekko then I think you'd be into this, if not then, well it's just not for you.
It's all pretty fun, great for summer and for people who don't take themselves too seriously. I picked up the striped shorts and look forward to wearing it with white poplin and navy blue shirts come summer. A designer I work with got them for herself along with a striped t-shirt in the same colorway. She's going to wear it with a good pair of heels and I think it'll be quite nice.
Of all the H&M capsule collections I found this one to be the most genuine and provocative. Also, there were a lot of accessories which were not bad either.