I just bought a Samsung 55" LED TV last week from Comet - got it for an absolute bargain price of £1200 down from £1500. I've been weighing up my options for over a year and i've just been waiting to pounce as soon as i found a good deal.
My only criteria is that i wanted a borderless screen, i.e. one with only a 0.5mm bezel. From reading online reviews, they all said Plasma's still offer better picture quality than the LEDs, but i've had a large Plasma for the last 5 years and i was ready for a change.
My TV is active 3d. The glasses are £15 each which i dont think is bad. Active 3d tv'd are full 1080p HD when in 3d mode as the tv is displaying alternate full-res pictures, whereas the passive system used on the LG's is showing alternate columns of pixels per eye, per frame i believe - hence only 540p resolution.
My TV has 2D>3D conversion too which can be used on any input source. It does a really good job... maybe 70% as good as dedicated 3D material. Playing XBOX in 3D is great... i even hooked up my N64 and played Goldeneye in 3D - but it wasnt that noticeable... I've bought a couple of dedicated 3D xbox games too... Crysis 2 and Gears of War 3. Only played them for 10 mins each but the 3D really adds another dimension to the games.
As for Smart TV... as others have said, there are tons of other devices out there that can do this i.e. xbox etc - but what i didnt realise is the TV now sees my NAS drive simply as an input source. Like when you switch between inputs, it is listed here. . I have a LOT of films on there, and scrolling through them has always been a pain - but the TV has a search function so i just type the name of the film i want to watch in, and it finds it instantly... this is so much nicer than streaming through my xbox.
All in all - im very happy. I wasnt interested in 3D or Smart functionality until i got them both, and i now love them.