Gaming Boulevard wrote a review of Exit The Gungeon, explaining why it's worth the struggle.
XBA says: A drastic shift from the first outing, but Exit the Gungeon still has its unique essence.
From PSU: "A sufficiently wacky and charismatic follow up experience to Enter The Gungeon and an enjoyable roguelite game. Regrettably, due to a number of flaws, it can't be appraised as the sequel fans would have hoped for. Exit The Gungeon probably won't win over any genre newcomers either. However, for existing fans longing for another crawl in the Gungeon, Exit The Gungeon just about does enough to be worth a look."
PP: Exit the Gungeon is a worthy successor to the fantastic Enter the Gungeon and one that fans of the original should enjoy. The cycling of weapons makes it unique, and at times frustrating, but exciting throughout. It's not as deep as the original but manages to maintain most of the charm and fun that made the first one such a gem.