I haven't flown JetBlue yet but am seriously considering them for a trip to Europe in summer 2025, so I've been reading up.
Like PP mentioned, they use narrow-body planes for transatlantic. Boston may be emerging as a hub for their transatlantic flights.
It's been widely covered in the air travel press and social media spheres, but JetBlue has replaced hot meals with cold meals on their transatlantic flights. Supposedly the cold meals are actually quite good. This is not a deal breaker at all for me, as I'm fairly price sensitive and the flights I'm interested are several hundred dollars cheaper per person on JetBlue compared to my local legacy carrier.
(Serving only cold meals has something something to do with specific planes and the number of ovens in the galleys and being able to staff a flight with one less flight attendant.)