There are pros and cons.
Well, it will allow you to lift more weight if used right because you make better use of the stretch reflex. The downside is that you can learn to rely on the stretch reflex to get out of the hole and if you only squat like that you will actually become weaker at the start of the movement (weaker in that you produce less contractile strength with the muscle, letting the reflex do the job). There is also the possibility of the bounce taking you out of position. This Is especially likely to happen if your core is weak or if you rack position in the front squat is not solid.
The best example I can give you is Pat Mendes (American/Brazilian weightlifter)… Pat has posted very high squat numbers yet when he does clean and jerks in competition his recovery (standing up, basically a front squat) from the clean is pretty much always hard; like he lacks leg strength… yet he squats huge weights. But all of his squats are bounced… in fact he has the biggest bounce I know. On the other end of the spectrum you have Clarence Kennedy (Irish weighlifter) who squat lesser numbers bu because of a previous knee injury he now avoids bouncing (he did in the past), in fact most of his squats are paused in the bottom. His recovery from cleans are A LOT easier than Pat’s even is Clarence is lifting more weight in the clean.
My opinion is that its fine to practice the bounce once in a whole but it should not be your regular lifting style. In fact you will get much more benefits from using a pause in the bottom position. The goal is not to lift more, it is to get stronger muscles. If you lift a higher number because of a “trick” then it doesn’t mean anything.
If you had to lift as much as you could for a special occasion (contest for example) then its fine to use any trick to move up more weight. But in training the goal is to get the muscles stronger… use techniques that make the muscles work harder.
I’ll use an extreme example: using a bench press shirt could make you lift 100lbs more (in many cases its more than that, but let’s use a conservative number for the example). It does so by basically catapulting the weight off of your chest. The shirts are very thick, thigh and elastic and when you lower the bar to the chest it is stretched and when you press the shirt does a lot of the work for you for at least 1/2 of the movement if not more.
Would it make sense to always train with the shirt on? After all you will use more weight…
What will happen is that your chest and front deltoid muscles will not get much stronger because their job is done by the shirt. You will lift more weigh without getting your muscles stronger.
The bounce is a little bit like that (but not as extreme).