I use lock on a hell of a lot, but it too is massively problematic, probably due the camera. Lock on has the benefit of giving you a tighter perspective to know what direction you should be parrying in, but it's a hot fucking mess when you're moving around a lot, and usually seems to have a mind of its own. Worse case scenarios have lock on outright ignoring some enemies (usually airborne) while the camera spins around for seemingly no reason, fucking with your defensive moves.
Also, now on 004, I'm reminded how much I loathe the wiggle stick shit in this game. The necessary wiggle stun shit on higher difficulties needs to fuck right off. There's zero feedback on what you're doing, whether you're doing it right, and how to actually get out of shit.