The biggest danger in paying for a subscription, at this point, is the big unknown whether Violet will be successful in getting all their issues under control. That is, there have been reoccurring issues with keeping _all_ of the paid services available, as well as offering stability and consistency in those services (reliability has been noticeably missing, Nabcasts have repeatedly failed, etc). Not to mention, after about 5 months, parts of the English my.nabaztag.com still requiring you to "guess what the French word means".
They've been able to avoid a full scale riot, so far, by repeatedly pushing out the beginning of requiring paid for full rabbit access. So, perhaps some clarification on their refund policy, should they continue with these issues, might be in order before putting down your hard earned cash.