I've looked at it.... Kind of interesting to see where your listings are ranking, but I don't really find it all that helpful, as my titles etc can't really be tweaked or added to all that much. 

I haven't used the tool, but I have a listing where the bot reckons I should update the title. As all the relevant information is already in the title and using the suggested 'improvements' would probably get it pulled for keyword spamming, I will continue to use my own judgement.