It is hard to use well at 1st level, precisely because of the duration. It's probably best around 2nd-3rd level, when it will stick around a bit (at higher levels, the increased duration typically won't exceed the creature's survival time anyway). Then it will get a few more attacks in, and be more likely to draw attacks from the foes (think of it in terms of augmenting the party's total hit points in that sense).
Also, note that if you're a cleric with an alignment domain, you get an extra round's duration out of summoning a creature of the matching alignment, since summoning (for example) a good creature counts as a "good" spell. That can be criticial for a 1st-level caster.