Being that the holsters are designed for drop leg use, they have two adjustable leg straps (with clips) and a velcro belt strap.
It is recommended to leave the blasters in the holsters for a while (or just store them in the holsters permanently) so as to maintain proper holster shape.
Note that the trigger is completely obscured by the handle.
The default position of the strap for the Sweet Revenge is for unprimed position, that is, the hammer is not back in the way of the strap.
Releasing the thumb-break strap simply requires pushing outwards with your thumb. At first it will be quite stiff but over time the snap button will loosen up a little allowing for easier draws.
To get a good strap fit, it is recommended to attach the snap button first, then move the strap into position and then remove the ruler.
A good thumb-break strap fit is important for easy strap breaking - if it is too loose then the strap will flex too much and will not break as easily.
Re-inserting the blaster by just shoving it straight back down into the holster is not particularly smooth (for the Sweet Revenge at least), as the top of the holster is not as wide as the middle, where the cylinder bulge is.
EDIT: With a little more experience and time, I've become more used to reattaching the thumb break single handedly, it's easy provided the thumb break strap is properly set up.
Having received them part way through the MHvZ event, I was able to get a little combat experience with them.
Like all other tac gear it feels a little weird wearing them for the first time, although as I used to run Nerf-made Sweet Revenge holsters a lot the only part that felt new and unusual was the leg straps.
Running around with them is very comfortable and feels very natural, besides obviously the leg straps which I'm not quite used to yet. Properly worn the holsters don't shift about much, and drawing is quite natural once the thumb-break motion is mastered and the snap button is loosened a little.
I did have an issue where my right holster came off my belt, which was caused by not properly attaching the velcro belt loop. It was purely my error, nothing wrong with the product. My left holster stayed on just fine and I was able to draw and use my left Sweet Revenge with no issue.
The one slight issue I've had is that because fully reholstering takes a reasonable effort, the holster tends to shift down very slightly, loosening the leg straps slightly which is a little annoying. The holster remains in place properly with the leg straps slightly loosened, but shifts around slightly more when running.
The several quick release clips allow for easy removal and wearing of the holster without changing the leg strap lengths or belt loop position.
I'm personally quite happy with them, they colour-coordinate with my other tac gear, and are far more secure than the Nerf-made plastic holsters I used to use. They're more comfortable to use, sit in a better position and move far less as I run around.
The MazoFactory holsters are not quite ready for release, but should be in the near future. Preliminary pricing for a Hammershot holster (the most likely first release) is looking at about 60AUD for a single drop leg holster in black, which certainly isn't cheap. Cheap drop leg holsters intended for airsoft and firearms can be had on eBay or otherwise for $15 and less, and there are a number of other aftermarket holsters available.
If you use multiple different sidearms frequently and don't favour any particular one, then the MazoFactory holster is not for you. MazoFactory holsters are designed and set up specifically for one blaster and are not adjustable for others. For instance a Hammershot holster cannot be changed to hold a Sweet Revenge properly. Unless you go and buy holsters for every one of your sidearms, you'll have one blaster that holsters well and the rest that holster badly or not at all.
If you're on a low budget, then again, these holsters are probably not for you. As mentioned earlier there are a lot of cheap non-Nerf intended holsters, and a number of less cheap Nerf intended holsters that still cost significantly less than a MazoFactory holster.
What the MazoFactory holster offers over other holsters is that it is a complete rigid shell rather than some plates of fabric secured with straps. As such while does not squish flat as easily, can't easily cater to multiple blasters and can't be opened up, it fits its intended blaster extremely well, is very tough and resilient, and also protects the holstered blaster very well. I certainly recommend them if that's your preferred style of holster, but again like with all tactical gear it may not be quite your style so it's always worth checking out all your options.