The poor netcode feels bad, as well as the long periods of black screens whenever you fail a mechanic. Having no SBMM means that a small group of players rack up a lot of wins and some players struggle to pass the first round and get enough for any of the rewards.
No anticheat in the client unlike the actual fall guys is a problem as well since this is a limited time FOMO event that's only going on for another 2 months then gone for who knows how long. People are going to cheat this and will they get caught? probably not since SE is not very good at banning cheaters in PvP and PvE in this game already.

The rewards not working correctly on viera also seems kind of lazy, instead of making rewards that work on all races, they just scale them down to make them look ridiculous.

Overall it's an ok idea but the implementation is not good, and chances are the feedback will not be acted on by SE, they're just going to bring this back once an expansion unchanged as a way to get people to resub and that's it.