Andromeda Shun is a fairly effective control unit, especially for an A-rank character. He is a very accessible Saint that almost everyone has, and with maxed skills he stands out for his reliable single-target restriction through Angled Chain - Thunder Wave, which can lock down one enemy for two turns under the right conditions. His Awakened Circular Lock Ring also gives the team some defensive value through DEF buffs and shields, plus an extra move to keep his tempo.
The problem is that his impact is still narrow for current standards. Most of his value comes from controlling one target, he costs 2 energy to maintain pressure, and outside that control he contributes limited damage and utility. In PvE, this gets worse because many bosses are immune to key control effects. He is still useful as a budget control option, but his ceiling in modern content is clearly limited.