Luci dear if you had such an experience why not tell the person asking about summoning spirits?
The OP of this thread asked a specific question which I couldn't answer ``yes'' to. It didn't occur to me that offering him my personal experience with summoning was relevent. I've never heard of the author that he mentioned and I'm pretty sure that noone would recommend summoning the spirit that I did.
So at thevoicesofheartie, I had a spirit following me for close to 12 years, and he wasn't pleasant at all. I managed to get it here but getting rid of it I just couldn't seem to do (I still think it's around here, it just doesn't speak to me as often as it used to). It was supposed to be a source of power and wisdom - A point from which I could gain strength and knowledge, it ended up being a spiritual torment that would not let me have any peace.
I can't say that all summoning experiences would work out like mine did, but I can say that you should at least be prepared for the consequences before inviting a spirit entity (any of them... it doesn't matter if it looks good in the book, don't trust what's written to be true) into this world.
This response is not intended to discourage anyone from attempting to summon spirits, it's simply meant as an example of what might happen if you don't know exactly what you're doing.