Alternate win conditions are great thing to have in my opinion and primetime is a really fun one. My only knock against him is that he is kind of slow when he isn't getting shown onto the battlefield. Usually that doesn't matter too much but it would be really nice to get something nearing primetime's power level for a few less mana.

I had a weird game 2 against grixis delver yesterday where I just beat him down with dark confidant through 2 blood moons and a pithing needle thanks to a mox diamond. He had locked himself out of most of his blue mana so he only had 2 ambush viper snapcasters as interaction and I could deal with both using a punishing fire and a decay. It was really fun to go the distance with a single confidant and wouldn't have happened if I didn't have something completely unrelated to the main plan to gamble for.

I think even a single molten vortex in normal punishing fire builds can help serve this role so there are lots of directions people can explore.