Reciprocating saws, Sabre saws....

[MetalMonkey]

Nope they are a bit rubbish. Most have a very short stroke. If your trying to cut metal it will generally just vibrate your arms off and not clear the chips particually well due to the short stroke. A better tool would be a Makita metal cutting circular saw or plasma.

For wood, I woodnt bother! A sharp handsaw will beat it or, a chainsaw, even the baby battery ones or circular.

The only good use for them is cutting roots, due to the saw blades being so cheap and far less sensitive to dirt than a chain.

They are primarily a demolition/remodelling/problem solving tool.

If you are able to cut wood with a handsaw, then a recip saw is the wrong tool for the job.
A recip tool is for cutting stuff out that is in-situ, where you can fit anything else, when its full of nails and bits of concrete and you have to be a contortionists to even see it and you have half an inch of clearance.
That’s where it shines. If you can cut it with a circ saw, you wouldn’t use anything else.

Same goes with the metal working, if you can use a portaband, or a grinder you would – but when you are trying to cut a bit of rusty exhaust pipe out in a tricky location with no access, again it can save the day.

Like I said, it is my least used tool, but the times I have used it, it has solved a very difficult task.
The multi tool I use a lot more, but again I wouldn’t be cutting a 8x4 sheet with one!

 

[Memmeddu]

It's own experience may be different than ours.
My brother uses it to cut bricks and concrete walls.
I use for things I'm not confident to cut with an angle grinder