Some 3D HDTVs actually kinda suck. The 3D effect can break down during fast movement and the active shutter glasses sometimes create a constant flickering effect. If you want decent 3D, check out these great sets recommended by Televisioninfo.com.
The Samsung UN55C7000 is a gorgeous TV with decent 3D emulation. Its 3D effect holds up pretty well under most conditions, the one exception being high contrast areas. The glasses seem to sync up with the TV better than most other sets, since there's barely any flicker while the active shutters are doing their thing.
The Sony XBR-52HX909's 3D effect is a bit inconsistent, but when it's working it's amazing. The 3D effect for background and mid-range objects is great, and the TV really only has a problem with things in the immediate foreground and the cliché "popping out of the screen" effect. The best part: even without 3D, this is a great TV. The XBR-52HX909 has great picture quality and Sony's incredible line-up of online content.
If we had to choose one manufacturer for a 3D HDTV, it'd be Panasonic. The TC-P50VT20 might be a first generation 3D HDTV, but it's still one of the best we've seen so far. The effect holds up well even in areas of high contrast or fast motion, and the active shutter glasses don't create an obnoxious flicker effect.