Frost is very last currently in Heroic Uldir and middle of the pack in Mythic Uldir. Probably because of the higher skill cap, missing just one shatter combo can drop your overall dps a ton so rotation timing is very important. With the heavy nerfs coming to snares in M+ other classes will have better aoe snares so we will lose our niche.
Definitly stay away unless like others say you have a nice guild who don't mind bringing along underperforming specs.