Painful.
We built our email marketing systems around Mailchimp because we thought they're size and history would make them a great partners. Bad decision on our part.
Poor UI, very very slow at times, difficult to use, creating journeys is horrible, customer support is indifferent. But we built using their APIs so stuck for the moment as we have better things to spend our money on. But if I were starting over, I would find a different emailing partner.
