4 months with the MK3
Since I haunted the forums long before I bought, I thought I would give my initial impressions to anyone doing the same.
Assembly: I thought long and hard about buying assembled then I thought "If someone paid me $250 bucks to put theirs together, would I do it?" The answer was Yes. That and I figured, putting it together would help me troubleshoot if anything went wrong. I put it together with the aid of my 15 year old daughter. It was ... fun. It helped that I had watched a couple of live builds (along with 3D Gussner, who apparently watches every live blog at any time).
Background: I also have a Monoprice Maker Ultimate (Wanhao D6 rebadge) and I was looking forward to having a larger range of materials. I design tools, jigs, fixtures, etc. 90+% of my prints are functional. Almost all of my prints are self designed. Started with Sketchup (talk about painful) and moved to Fusion 360.
Ordering Process and Communication: Placed the order, felt like it went into a black hole. Ordered before they said how long the wait was. So I had "Its shipping in November, so I should get it by Christmas easy" dreams. Not so much. Website said, "If you want to receive your printer with textured powder coated spring steel sheet, please contact us and we'll hold your order until late January 2018 when they're expected to be available." My label was created on Jan 30th and it still said that, so I was like "Score"...um... wrong. They still don't have powder coated PEI sheets for people who don't have 100K YouTube viewers. Still can't even place an order (I can backorder a MMU 2, but not the steel sheet?).
Initial Impressions and False Delusions: Every video talks about how it is silent. Compared to the D6, it is. Compared to my imagination, its not as quiet as I had hoped. My wife still doesn't like it printing on my desk. She can take my table top fan, but not the 3D printer. I also had heard about how wonderful PEI is. Turns out, its not magical. It has somethings its good at and some things it bad at.
Is this thing Beta?: Sure feels like it sometimes. Prusa MK2 was always the "Gold Standard" for print quality. MK3 was supposed to be better in every way. It's got "Smarts". I've had to update the firmware multiple times. The crash detection would go off for no reason (when there wasn't a crash) and would ignore crashes and keep going. I've had more air prints / shifted layers / etc. on the MK3 in my first two months than I had in a year on the D6. Print quality started out pretty good but not amazing. Call it 10% better than the D6. It keeps improving. I haven't had a shift in weeks until I had one two nights ago. They put out a "replace the braided cable with textile wrap" notice but don't sell textile wrap or give you a link to Amazon to buy the right stuff. Parts have been redesigned multiple times (one notice I got the week I finished assembling the printer).
Things I love about this thing: (1) Removable Build Plate (which I love even more now that I have purchased a BuildTak flex sheet and put BuildTake on one side and PEI on the other). (2) The ability to carry it. The frame makes a great handle. I drag it back and forth to work some days. (3) Put some Windex on the PEI and PETG is magical. It sticks when printing and comes off so easy. (4) Updates. They keep updating it, and it keeps getting better. (5) Community. While someone will say, "adjust your live Z" on Facebook no matter what the problem is, you can always get someone to help. (6) Quiet. Yes, its not magical, but it isn't THAT bad. They just made the motors quiet enough that the Fan, Power Supply and Bearing Grind will bug you. (7) The screen and menus are straight forward and the white on blue is pretty.
Things I hate: (1) I don't like the open frame (other than ease of carrying). It makes making an enclosure harder. People set things behind the printer and you can't be sure you wont hit them. (2) The compact hot end assembly gives you good z print height, but I miss that you can't see small prints The fans and shroud obscure the print nozzle. Sure the D6 had awful cooling, but I could see the magic of the printing. (3) Cabling without removable connectors. I would much prefer connectors and wiring harnesses to "run all the wires and zip tie them or spiral wrap them, I mean textile wrap them." Slic3r is not as user friendly as Cura. I don't like the UI. But it is powerful.
Things I think Prusa should add to the store: They should have a plate pack. It would include multiple double sided flex plates with different build surfaces for specific Applications: BuildTak, Garolite, PrintBite, etc. They should also add the textile wrap to the store. They should allow back order of items they know they will restock (Powder Coated PEI / Prusa Orange PETG / etc.).
Things I would like to see in future products: I would also love to see 3D printing get FASTER. I would love the ability to send a job to the printer via wifi but have the printer own the print (vs OctoPrint). I would love a touch screen with better visualization (little things like "Z: 2.24 of 25.5"). I don't want a much bigger printer (No I don't need 500 x 500 x 500), but I would love to see either the X or Y Axis get bigger say 300 / 350 or 400. I would love to see Prusa release the E3D tool changer concept shown at MRRF (Core XY / HiWin Rails / Tool Changers / etc). If you could make it have plexi inserts for an enclosed chamber, even better.
Things that made me happier with 3D Printing: Slic3r 1.4 Alpha with Gyroid infill. Its fast and strong. Getting a steel sheet with BuildTak on it. Getting extra SD cards. So I always have one in the printer and one in the computer. Fusion 360: Oh my, this program thinks like I design. It makes me have positive feelings for Autodesk at least once every couple of days.
Would I recommend it to you: I am happy with my purchase and where I am now. It was more rocky than I expected but not too painful. If you like to design items, yes, this is a great printer. If you see lots of models on Thingiverse that make you want to print them, yes. But beware, after you start 3D printing things, you will start thinking, "I bet I could design and print something that would make this better...."