I'd be very interested what problems you were having with them and at what scale. If this is a private topic, we could do it over email or some other medium if you like. You can contact me by any of the means listed here: http://kovyrin.net/contact/
Aside from that it was mainly nit-picky type stuff, but still things that were annoying (networking issues between DCs, networking issues between pods, internal mirrored apt-get repos going out of sync, API is kind of blah, etc).
We use docker so having a few bare metal machines with tons of containers on them wasn't a great HA setup (for us at least), even running in two data centers. The fairly quick setup time though was a nice selling point.
When we went to AWS things just kind of worked. The API was easier to use and the GUI portal was way nicer/stable. So far we have not had any odd issues with our instances, but we also typically run them at about 50% capacity so that might be why. It is also still early so maybe things will come up in 6+ months that send us back to SL :)