After staring this thread, I purchased 2 more of the Walmart Slimlines (the Walmart versions of the Spitfire).
Both had a lot of vertical play, about as bad as any lock back I've ever handled. Vertical play doesn't bother people but bothers others. I'm in the latter camp, which may be because I work as an engineer and I have a hard time abiding things that don't work as intended and I'm pretty sure the vertical play isn't intended.
There is so much I really, really like about the Slimline and I say that as somebody who owns only traditional knives. It's very light, the blade shape is great, and it opens and closes one handed very easily.
I may get around to calling them to find out if this is something can be addressed.
In terms of serrations vs plain edge, here is my take. Perhaps others will chime in.
I think serrations make sense if you cut a lot of rope (or other fibrous material) and if you don't sharpen your knife often. Even when dull, the serrations can "saw" through rope or meat, just like the dull steak knife you encounter at your local restaurant. I find serrations do a poor job of working with and carving wood.
I think plain edges work and carve wood better and do a better job slicing through things like fruit or cardboard instead of tearing through them like serrations do. But, plain edges require on-going sharpening to keep them performing well.
Welcome to the world of knives! My recommendation is to learn to sharpen. I found a guided rod system (like Lansky) helped me develop my sharpening skills on bench stones.
Hope this helps.
