Like what was it's original purpose? We've only seen 2 so far Voyager and the Bellerophon. Voyager was originally to capture some Maquis so we can say it could hold it's own in battle I suppose if they came across some Cardissian Ships. And she held her own in the Delta Quadrant very well. The Bellerpohn was used to ferry diplomats so Starfleet or Admiral Ross had to have felt very confident in sending that class of ship alone to romulus. So my best guess is that it's a long range vessel maybe not tactical like the Prometheus but...