Most of the videos I've watched thus far on my 55LM8600 have been side by side. Side by side looks soft and the resolution drop is quite noticeable. Blu Ray and Top-Bottom 3D aren't half bad though. The resolution drop is there but you can forget about it at times. Frames seem to move a little smoother on passive, although I have no Idea what settings the sammy in the store was on. I leave my LG set to smooth Trumotion. Something to consider is that A LOT of content is side by side, passive's weakness. The picture on active is clear and crisp no matter the 3D content. This is what struck me about active, the screen was so clean and clear... at times. It seemed to me that the main focus of a scene displayed very nicely on active but things in the background tended to have some small crosstalk problems. These problems aren't glaring but they generally aren't there on passive. I didn't have any discomfort with the active 3D glasses, brightness was also not an issue.
For gaming, remember that HDMI is limited in what kind of frame packed 3D signal it can send at the moment. It's either 1080p 24hz or 720p 60hz. AMD has been able to squeeze 1080p 30hz out but that's the current limit. For most, you will be gaming at 720p with frame packed 3D. An advantage to passive is that a 1080p 60hz interlace signal can be sent, so it's possible to game at 1920x540 (I know 540 isn't exactly accurate but it sure isn't 1080) on passive vs 1280x720 active which seems a wash. The difference of 1280x720 and 1280x540 also doesn't seem that dramatic of a drop off it interlace is unavailable. Active can do 1080p 60hz in checkerboard 3D but from what I've read it causes input lag and is still not quite 1920x1080. I have also read that some active sets can receive an interlace signal but I'm unsure if this is true.
In the end, I'm right where I started pretty much. Pros and cons to each. I would love to hear more about the frame rate/tearing issue while gaming on active. This is pretty much my tipping point. I could be happy with passive but getting a crisper hi res picture with active is tempting as well.