I bought this product a few weeks ago and I've explored it enough to be able to review it.
First things first, I can say that the shipping service worked very well: in exactly one week after the seller notified the shipping I received the Cart Flasher. I just found the shipping costs pretty high for such a small and light object even having tracking (which stopped to update the informations once it went to Madrid) into consideration, hence why I did not classify the shipping service as being perfect.
The Cart Flasher has a phenomenal 3D printed shell that does protects the device for small accidents so I can definitely recommend people to spend extra to have the shell, it is worth it (especially if you are clumsy). The product does not come with a MicroUSB cable but anyone can get one easily. I had no issues with the installation of the drivers and the software itself. However, the documentation could be more user-friendly as I am certain that not every future buyer knows certain terminologies or other concepts about the Game Boy software/hardware and can be a little lost when starting to work with the Flasher for the first time. I personally had some trouble to figure out how to successfully inject SAV/RAM files back to the cartridges as there was nothing explaining me that in the troubleshooting, and I did not even have a response from the seller after messaging it (hence why I only gave 1 star to the Communication: my contact was ignored). I eventually figured out how to do it but I would definitely recommend the creation of a quick-start guide for future buyers to have more clear instructions of how to fully take advantage of the flasher for strandard use. Compatilibity-wise, the Flasher worked with all the 11 games (Pokémon are included in the list) without any issues.
To keep it short, despite of minor issues I am very satisfied with the product. If you are among the slice of European Union players who are scared to lose all your efforts done to your Game Boy battery-powered saves you will definitely need this. It is worth noting that this is the best alternative I found opposed to others that are recommended online but are currently in highly galloping prices!
I got this for some homebrew games that I've worked on over the years - this is likely the closest thing to an actual cart release they will get. It allows me to try the games on close-to-real hardware, and uncover issues emulators might miss. The cart flasher combined with this allows flashing the cartridge on Windows, which is nice since I've had to use a linux VM for the other cart I have. Overall, it's simple and gets the job done.
My order has a fault with FRAM or with the connections going to the FRAM. ROMs can be written and read to the flash without an issue (implying both the flash and MBC work correctly) but saving never works and reading RAM results in a file of all ones. There are also severe graphical issues in the pokemon games I've tested. NBA 3on3 and tetris both work fine. I originally thought this was due to the FRAM chip chosen not supporting multiple operations per /CE (not chip enable) edge but according to the seller his design works with the ROMs I've tested so it must be a bad cart. I noticed that the via location tolerance is quite high and it's possible that one of the vias shorts something it shouldn't. The seller has offered to send me a replacement and I am happy with that. The PCB is noticeably thicker (1.6 mm) than normal GB carts (0.8 mm) though this isn't a huge drawback in my book. It makes for a snug fit and you can be sure there will be good contact. This will negatively affect the life of the female side's pin springiness (a part that is getting harder to come by).