If you stick to the apps that are indicated as being well supported it’s good. The main reason I use it is because I’m part of a team that includes people not comfortable with the command line so having a web interface to manage a server means not everything falls on my shoulders.
Masto to Lemmy works OK. Lemmy to Masto not at all. I have a hazy memory of someone posting to Lemmy from a Friendica instance but might be wrong.
Generally, its a bit indifferent.