I also cannot comment from personal experience; I'd just like to point out that the OP contains a pertinent question that the designers have worried about the last few years. Pets (or more specifically summoned/conjured aids to the PCs) caused quite a bit of a stir in 3e, as combined with ubiquitous layering of spell effects, could dominate encounters and push fellow PCs out of the limelight in the right circumstances. Since then, the devs have been very cautious with summoning in 4e & 5e, much to the disappointment of summoning fans. The whole sacrifice an action to let your pet have an action was a direct carryover from 4e and seen as a way of limiting pets from dominating the action and taking too much time.
It seems to me that the new summon spells are more specific and not as open ended in the Conjure spells in the PHB, usually offering only one summon with two or three minor variants, so that should help somewhat with the 'analysis paralysis' that can sometimes happen with these spells. Though it does add an extra participant to the combat, there's really no way around that. Overall, it seems that it is worth the increase in complexity for those who want such things, as the more strict limits on what the caster can summon and how they can enhance their pet seems to be better a design than in the past.