i summoned a blue phantom last night for the first time to beat the Tower Knight...it's sooooo fun! the ghostly teamwork is perfect for the vibe of this game. it's like even though you are always outnumbered...you are never alone
 
but i heard that when you get summoned as a phantom you can't get any souls or items, only your body restored, is that true?

No, you get souls just not items.

You get half the souls that normally drop per enemy and have no risk of losing them.  You also get the opportunity gang rape black phantoms which is so damn satisfying.

I've never found soulstone drops when I was being invaded.  But I still have a 4/2 win-lose ratio.  The four wins were the first night I got to 1-3, got invaded one after another.  It was intense.

I just had my first Black Phantom invade my game today.  My initial reaction was "Oh crap, I can't handle this guy!"  I haven't been playing long and I am not that high of a level.  Well it happened in 4-1.  I only killed the first skeleton when it happened.  So I turned around, and here is this guy, glowing red.  I ran up towards the stairs, knowing he would see me and then I'd cut out.  I then ran to my left (away from the cliffside) and walked back down towards the stone wall and waited for him to pass through the bottlenecked opening.  He ran by unaware, I sprinted behind him and stabbed him in the back and he died in 1 shot and I got a ton of souls!  It was awesome!

invading and being invaded is one of the funner things in the game. nothing more satisfying than some chump trying to gank yo ass and then taking him out. also hate when you invade and it turns out there are a like 3 dudes in the world and you get insta-gibbed