The customer service is great! They are very responsive to our needs when we have questions or issues that need resolving quickly at no extra cost (like an expired certificate).
I wish they could do more than just DNS resolution - but this isn't really their focus area so it's not something i can complain about too loudly :) We've been working together now for over two years as part of one project which has required us both work closely from time-to-time solving problems such as SSL certificates expiring etc., plus being able solve any tech support issue straight away without having someone come out if needed.