I usually sit in the exit row (remember, you want the SECOND exit row or you may have no recline), but didn't notice the heat, although in the summer I often travel in shorts and a T-shirt.

I hadn't noticed any service decline. What I really like about Jetblue is that they have a large variety of snacks and leave them out for you to take what you wish, including water. Nice extra touches.

My last 2 flights were on-time, even a bit early. I've got 3 roundtrips in the next month, at different times of the day, so I'll report back if I notice any particular lateness. I always assume that these quick-turn airlines are susceptible to backups if an earlier flight is ever delayed, but I haven't noticed it on Jetblue yet. It could be because many flights are out of LGB, quite possibly the least delayed airport in the nation.