I like lockbacks (a la Buck 110 and similar lock designs), but I have encounted have one problem with enough of them that I dislike buying one without actually handling it.
I'm not dainty or weak-fingered, but I find that with some lockbacks, disengaging the lock requires you to exert a large-to-painful amount of pressure on the release to make it unlock. It's as if the locking nub fits too snugly into the tang notch to release smoothly when you press the unlocking bar.
In one Boker I have, you can hear a 'click' as the nub disengages abruptly. This occurs after you've pressed so hard that you're thinking of using the hard edge of a table (say) to press the locking release sufficiently to close the knife. That kind of thing is a disappointment when you are forced to buy a knife without handling it before purchase.
I understand there's a safety line here between locking up adequately and being too easy to unlock. And with years of locking and unlocking, the faces that bear on each other in a lockback will wear in. But, dagnabit, if a knife is so hard to unlock that I avoid using it... Well, that knife won't ever get worn in to the point where it's easy to unlock.
Linerlocks don't seem to experience this, but some are quite stiff, which may pose a learning/coordination problem all its own for some (though not me). Again, handle before buying — or take your chances.