Are you kidding? It's painful! Don't get me wrong, it's much much better than nothing and I'm very grateful they made it, but if you're doing more than a handful of names it gets real tedious real quick. And it seems to be impossible to correct mistakes, even if you've just entered a new name yourself and notice a spelling error.
Well that's easy enough to accommodate. Download the name mappings from the server, apply to the local decompiled obfuscated code by gradle or whatnot, then after refactoring the names, run a gradle "diff script" or similar on the client, and send the information back to the server again.
-TGG
I actually find it more convenient. I keep a MCPBot DCC chat open in the background behind my IDE, so when I figure out a name I can just directly hop it over to MCPBot.
And if you need to change a name you can go to #mcp, they can help you.