the monoprice mini delta.

I actually have no initial hardware issues with mine.
With a 0.4mm nozzle it works extremely well (and that's currently back in place until I get round to moving the extruder).
People have issues with the build plate and the auto levelling (works perfectly on mine).
Some of the people on the mmd have pretty much rebuilt the entire thing.
I don't think it's necessary.

The main issue is the bowden tube.
It's much longer than you'd expect on a machine this small and it's really badly placed.
I intend to drill a couple holes in the frame and move my extruder to the same place I have it on my he3d k200. That optimises length and reduces the angles you have to push the filament round.

I did manage to print a few items with a 0.25 mm nozzle - and the results were pretty amazing. But when you got to any kind of decent height - say about 40mm - the system would clog and the extruder would start to grind the filament., Basically at that point the bowden tube was too long and at too sharp an angle for the extruder to push the filament through the hotend.
With the 0.4mm nozzle it manages, but with the increased back pressure you get from the tiny nozzles - it just causes problems.

The power supply is really weak - 3amp. As long as you stick to pla - bed 50c and hotend 200-215 - it's actually fine.
But anything much over those temps and it really struggles.

You can get a 10amp psu, but apparently you need to change the firmware to utilise it properly.

But then you can buy recon units for a little over £100 - so at the end of the day you do gets what you pays for.

I like mine, I got it spefically for tiny detailed items (not figures, just things with small internal mechanisms).
Or a tiny funnel for refilling those little tabasco shaker bottles.
Did a tiny one with a stiff flexible pla. came out amazing, so I decided tp print one with a larger funnel part - and that's when I hit the height issues and the nozzle blocked and I eventually put the 0.4mm back and it's working fine now.
Just not for what i wanted it for.

So I will move the extruder and shorten the bowden tube and try again.

But yeah, if you are prepared to tinker - it will definitely produce near resin quality prints.
But not something I would recommend for a first timer.