I've been messing around with customs with every character since the JPN 3DS release, I think it's like Kong Cyclone, it'll throw you off and it does add options but once people get used to it, it's not super crazy yeah (though DK's Kong Cyclone is a bit different in that it pushes him from mid tier to like a high tier character on a stage with platforms). I think it's pretty effective in mixing up with PK Fire to punish rolls since PK Fire can be punished pretty badly if the opponent is watching for it. It's probably Ness's most interesting custom for sure.
Speaking of Kong Cyclone, PSI Vaccuum can clash with it in some hilarious ways.
As a Lucas main in Brawl it's pretty disappointing the ported over PK Fire and PK Freeze aren't even as good for Ness. PK Fire is much more laggy.
I agree it would be more useful against Kirby and Jigglypuff but those matchups are rather easy for Ness anyway.