It was a good value at the time of its release, but it's far from ideal today. In order to unlock all the games (including S3&K) you have to boot and exit certain games as many as 30 times. The games don't display in the correct aspect ratio, it isn't quite 4:3, it isn't quite 16:9, it's just weird and stretched.
The performance isn't great, sound effects sometimes play out of sync. This is not the only collection from this era to have weird audio problems (likely as a result of trying to constantly load it from the disc), I've had weird problems with Mega Man X Collection and Namco Museum in the past, but they're generally flukes that either fix themselves or go away with a reset; with Mega Collection Plus the issue is rather consistent.
If you want a "pure" experience, get the original cartridges. If you just want to play all these games, there are much better ways, both official and unofficial, to do so.
The performance isn't great, sound effects sometimes play out of sync. This is not the only collection from this era to have weird audio problems (likely as a result of trying to constantly load it from the disc), I've had weird problems with Mega Man X Collection and Namco Museum in the past, but they're generally flukes that either fix themselves or go away with a reset; with Mega Collection Plus the issue is rather consistent.
If you want a "pure" experience, get the original cartridges. If you just want to play all these games, there are much better ways, both official and unofficial, to do so.