Well I guess the goal as pac man is to make the neutral game not so neutral, so however they choose to approach or escape can be handled, trampoline is one of the three tools he has but I have trouble getting it out without getting punished.
In addition to what Fromundaman said, trampoline is usually 100% safe if you can grab a ledge. You do have to deal with getting up from the ledge afterwards, but you should make it without taking damage.
As usual with Pac-Man, you have to heavily take into consideration who you're fighting when you decide how you will set up. With trampoline, it's not that difficult to evaluate who will have an easier time punishing it.
Low mobility characters like Luigi and Ganon virtually can't punish for a full retreat trampoline, even on whiff. You can get away with spamming it against characters like them.
Characters like Mario, Wario, Yoshi, and Jiggs have rather high air speeds. On whiff, you may be able to avoid getting struck before your shield comes up, but you can rest assured that the opponent will be right on your tail, and you may not be able to avoid getting grabbed.
Characters like Fox, Falcon, and Sonic can easily punish you for whiffed trampoline unless you grab a ledge. I think they can punish you on hit at lower % unless you grab ledge.
Just keep playing the game and over time you'll get a feel of who you can get with trampoline more often.