Yes, I'm having problems getting used to this, as most who have posted here. Like everyone else, I used the down button to target myself in both ffxi and this, before the change.
I almost died doing a simple faction leve I've been doing forever lol. Aside from the 'habit' of the down button for self-targeting, the thing I don't like about it is that to switch back and forth in battle situations, you need to close your action bar. Most likely because I'm not used to it, once you close down the action bar, it's easy enough in the routine to change the target default and find yourself targeting a friendly or yourself when you open the action bar back up, requiring another action bar shutdown to re-target the enemy, or vice versa for cures/heals.
I'll reserve judgement on this, but right now, I find it cumbersome and quite confusing. Nothing beats the good ol' days of ffxi macro's with /ta <stpc> or <stnpc>. I guess we all were spoiled by that - it was automatic lol. If macro's ever become the ticket for ffxiv, it will negate even having to open the action bar, in which case I would vote to have this newly installed targeting mechanism removed.