Skaven - Clan Skryre Rat Ogre

So one of the members in our campaign will be running skaven and has indicated he intends to bring the Clan Skryre rat ogre out at some point.  I have never played with or against one of these so I wanted to get your opinions about the character and tactics.
(I used the search function to look for a topic about this but came up blank. Sorry if this has been done before)

1) Is the Skryre rat ogre typically worth its cost?  (100gc plus 1 wyrdstone upkeep) For skaven (larger warbands) I could see the value of the 1 shard being 5-15gc upkeep.  Is this a late campaign addition or could you see it being taken early on?

2) How effective has it been in the games you've played?

Thanks again.

They are very scary but the chance that it malfunctions is a high risk to pay. they are are great for new warbands but once you have more than one 90xp hero they are not a necessity.

1) Yes take early on.

2) Very effective until it explodes and the table explodes in laughter