The interface was easy enough for me as an average user; I didn't feel like it slowed down my computer too much or anything during normal usage (although there's no doubt that some people would have issues). It did not give any warning when something went wrong - sometimes you'd think everything had gone okay but then realise later your coins were stolen! Not great if this happens over time though because at least they are still making money from them so don't lose hope until all traces clear…