Great to see Futurama back. Personally, I was quite happy with both episodes, and I thought Rebirth in particular fit in well with the established quality of the series. It's not up there with The Sting or Godfellas, but it's a decently clever adventure that mixes in a little bit of everything that is Futurama in a funny, fast-paced story.
In fact, I was a little surprised by how genuinely funny it was. Even the movies had some slow spots and rarely got to the point of rapid-fire joke-telling like the series, but Rebirth brought that back really well, particularly with Farnsworth (just about every line of his was great). There were a few weird or flat moments (the umbilical cord gag was done better in The Simpsons and doesn't really make sense here--I mean, Hermes doesn't even flinch...how much would that hurt!?), but I'd say this is on par with Futurama's sense of humor. Bender's subplot was enjoyable, mostly due to a bunch of fun background moments and they never dwelled too much on him. I also liked the return of Randy: "Do the Bender!" "No thank you." "I SAID DO IT."
The story was also enjoyably creative, and supplied a twist I didn't see coming. There was quite a number of plot points stuffed in here, which made some of it feel rushed (Leela awakening from the coma, Bender's doomsday device not really being a big explosion at all, Fry coming out of the birthing machine just in time). And the Terminator thing was sort of goofy; I think it'd be cooler if they went off together but didn't shed their human shells, and possibly had a role as doppelgangers in a future episode.
The other scene that felt strange to me was the professor's invention, which essentially cheated death itself. Since death was handled with a lot of weight in several past episodes (most notably The Sting), it makes it feel like our heroes are practically invincible. I mean, Fry was revived after being crushed into a gooey cluster of cells and hair! I'm worried this will cause story problems in the future if it involves death or near-death experiences.
Also, why were Zapp and Kif's heads unharmed when the shields only covered the PE crew?
Anyway, some story snafus aside, I liked it quite a bit. I wasn't really feeling the emotion as much, but the gags and creativity made for a very entertaining return to form. Looking forward to seeing more Futurama!