I don't personally own the Spyderco Manix - I don't care to have a lock-back for an EDC folder and I don't like thumb-holes.
I must admit I was a little leery about the thumb hole at first, and it took me a long time to get used to the lock back because my previous EDC was an Emerson with a liner lock. The lock on this thing is so solid, it sounds like a gun action going into battery when you open it.
Once I got used to those changes everything was great. The only thing I'd do differently next time is not get the combo-edge. The S30V takes such a great edge, the serrations are not really needed. I cut a lot of line at work and thought I needed them but I find that I don't.
There are only 2 things I don't like about this knife, and I plan to fix one of them.
They are: Thumb hole is so large, it makes the spine arch and folded, the knife is very wide. With a stud, this knife would be much more pocket-friendly.
The other thing is it would be nice to have a little more traction grooving cut into the frame and liners along the bottom, and particularly on the top at the butt end for the stab grip.
-C.
edit: minor changes in wording because it's too early to make sense the first time 'round.