My experience with SeventyMM has been a mixed one - good support, average content, poor website experience.
SeventyMM have been plagued by delivery issues since their inception, both of DVDs and their shopping items. But their in-house customer support rallied around admirably and ironed out all the issues that I’d faced, from late deliveries to non-deliveries, even to the point of conferencing me in with the outsourced delivery people.
Their content of DVDs is limited, and often not to my liking. But I’m hoping that they’ll change that and improve with time.
Their website design needs considerable improvement. Things are not easy to find, do or execute. I suppose they need to do user acceptance testing on external users, rather than implement something that just "looks good".
Overall I would recommend them.