If you don't have cartridges, at the moment it may be hard to justify the price. The reason is the screen - it is so high resolution, it will emulate sub-pixel LCD screen characteristics from the original GB/GBC/GG screens, BUT ONLY for physical cartridges OR GB/GBC games that have been converted to .pocket files (you can do this easily, but it's still an extra step).

So for most people, it will play similar to the much cheaper Miyoo Mini or other Chinese emulation handhelds.

However, there has been a long-held expectation that Analogue will enable display mode options in the OpenFPGA cores, which would erase this handicap and mean absolutely, if you want to get the real experience of these systems, this is the only game in town. But it hasn't happened yet. You may not be able to buy a system later though, when it happens, so it's kind of a gamble.