I've watched them and I say do it. But don't take it too seriously. Indiana Jones movies (in particular the first 3) are fun to watch, but don't think too much. The storyline is simple, yet good. If you start overthinking it, you'll have a bad time.
Harrison Ford is awesome, his reactions are funny, and the acting in general is good. Don't expect too much from the special effects though, these movies are old (you can see explosions are fake, and the giant ball of death is clearly just Styrofoam).
The fourth one, I recommend watching drunk. Ford is still great, but that's it. Watch it drunk, and it'll be much funnier.