Review from a casual user here.
Now that the prices have come a little out of the stratosphere I recently bought the 5040ub from BB for about $2200, and with a couple hundred in CC bonus cash back it was even cheaper. This is my first projector. After I bought it a friend was telling me about BenQ having "true" 4K at a lower price point now, but when I look at the features and image quality I'm not sorry about my decision. Now I don't have a dedicated theater room or space, and this thing will not be mounted. I bought a cheap (like <$100) Chinese 120" screen on a flimsy tripod (white with black backing) that I setup in front of my TV, split the audio into my old soundbar/sub (behind the screen) and setup the 5040 on a projector stand. This way I can setup and tear down "movie night" rather quickly. As it turns out the Epson is rather a bulky projector for this type of usage, but at the same time the remote-control lens shift, zoom and focus features are absolutely invaluable if you're going to do it this way, because it needs tweaking every single time. It was a bit tricky finding a laptop/projector stand with a surface large enough to support this projector. The one I did find has a thick but plastic table top, so it actually bows slightly at the corners under the sheer weight of this projector. Its not a permanent fixture though so I don't worry too much about it, but I wonder if there is a truly good stand for this projector out there.
I admit to knowing little or having much interest in tweaking the picture settings much, and just stick to the preset modes, but I am more than pleased. The picture, the color, the brightness on this thing are absolutely gorgeous. It turns my living room into a movie theater. I've never tried 4k and don't really have any 4k devices or content, but HD looks wonderful and even good quality DVD and SD look great, if a bit softer. The projector itself is plenty quiet.
My 1080p LCD TV is rather old, still working great and I'm happy with it, but it pre-dates the whole 3D thing, so I never got into that. I also have an Xbox but never bought a proper blu-ray player. But I was recently given a new LG 4k UHD 3D bluray player, very basic dumb disc player. I don't have any 4k discs but decided to get some glasses and try 3D. I found some cheap $20 RF glasses online and wasn't expecting much, but tried it out with the 3D Rarities bluray. I really didn't expect much, but I was kind of wowed by it. This is the best 3D experience I've ever seen. How can 3D in theaters be so crappy and this consumer-grade projector be so good? I didn't have to squint, blink, refocus, cross my eyes, or struggle to see the depth and 3D effect, no blurring, image still bright enough, you just look through the glasses (which paired super easy) and you see stereo vision, the way it should be. 3D is still a gimmick, but it could be fun on occasion. I didn't even try tweaking it, I just put a 3D disc in and played it. The Epson with the quality of the 3D picture on a large projector screen makes it something actually worthwhile, whereas 3D on a much smaller TV set of almost any reasonably available size just doesn't seem like it would cut it. Wearing glasses to watch 3D on a little 50-60" TV from across the room just seems like it would be kinda silly to me, which is probably why it never really took off and is slowly dying, but with the larger projector screen it really works.
So as amazing as the 3D quality is I then decided to try the 2D-to-3D conversion on some of my other content. I remember seeing this feature years ago in old versions of PowerDVD and hearing that it actually kind of worked, although again I didn't expect much. Well in Epson's case I don't know why they bothered. I tried it with several types of content, and I tweaked the 3D depth and changing the setting from Low-Med-High, etc. Nothing I did would introduce any discernable depth into any of the images I looked at. Maybe I'm missing something, but all it seems to do is force you to use 3D glasses to see the same old 2D content. Nothing really seems to look very 3D, other than the entire screen image maybe seems to be floating in space. Oh well, it was just a gimmick anyway.
Anyway, I'm extremely happy with this projector. I've run last year's Roku streaming stick through it (1080p I think), Xbox One, the LG 4K player, streamed some TV with Sling, Netflix, Amazon, etc. And lots of movies, HD and SD, from my NAS. Phenomenal beautiful bright picture. I don't need a projector every day but its definitely nice to have and is the best way to sit back and enjoy a film, and maybe someday I'll have a situation with a dedicated space for it. At the same time I could be very popular loading this whole kit in the truck, maybe with some cheap high wattage speakers, and taking to parties and get-togethers.