It's great solo for ranged AT's, but it's usability in teams with melee characters or primaries with melee henchmen is limited.
Yup FB absolutely rocks! 
But as Max said, not for teams with melee chars or for sets with melee troops, as the radius is huge compared to dispersion bubble. I would NEVER pick FB for Thugs/Ninjas or Necro's as force bubble is such a good power I couldn't bear going FF without picking it!
Things I found that can run through it are:
1) Carnie Strongmen
2) Rularuu Brutes
3) Most Elite bosses (not all...I pinned the wailer one in a corner and my bots burned him to death )
4) All AV's
Otherwise pretty much everything else can't penetrate it. It will draw quite a bit of agro to you, however with the defense changes and Bodyguard in i7, I can see it being far more useful than PFF
This power is awesome, do people realise once you have it on, no mobs can run through it? 'cept for a few bosses here and there with knockback protection. As a bot mm once i'm running force bubble my pets can lay waste on everything and not caring about nasty mobs with melee attacks. Wich is very handy since bots are weak to smashing!