Welcome to the forum!
Your question is very broad and tough to answer without knowing the size and shape of the dents you're referring to or the mechanics of the dent puller you're referring to.
If the dent does not have sharp creases and is not real deep, a dent puller may have good luck getting the dent mostly out without cracking the paint or being real noticeable.
If you're talking about the type of dent puller that has a suction cup, those tend to only really work on large, smooth dents. If you're referring to dent pullers that use a hot melt glue and a little tab that gets glued to the paint, those work okay on small dents such as hail dents and door dings. Again though, the dents cannot have creases, be real deep, or have cracked paint already. It's also possible with these types of pullers to over-pull the dent. They take quite a bit of trial and error to get a good feel for how much to pull and which size tab to glue on. Some of these kits also come with a stick for leveling the dent if/when you do over-pull it. It's surprising how little tapping force is required to flatten the metal back out. That's a caution to you - don't tap too hard, light blows are typically sufficient.
-Rod