The first episode wasn't bad. It wasn't great either. The second episode though... geez that was bad.
They were both pretty awful - but the 2D one was awful and tragic given that it had a decent premise (gang ends up in flatland) that was mangled.
As for what happened to Futurama? IN order of least important to most
-It got political - weird random leftist bs mostly from Verrone in the last few seasons. Nixon as President good, Gore trying to save the universe with Gary Gygax, also good. Birth Certificate from guy from future episode - stupid.
-It got too into 'topical' humor - e.g. the iPhone episode, instead of having fun with the future the writers got lazy and just started using current themes.
-It got way too self-referential - e.g. the reference to 'another one of Fry's dogs' In this episode.
-It got too into 'gross humor' - iPhone episode with the vomiting 2Headed llamas or wtf - absolutely unfunny.
-It got too into 'potty humor' - e.g. the VGINY episode. Not funny.
Basically the writers tried to adopt some of the things that make South Park work (topical, sell-referential, gross, potty humor) forgetting that Futurama wasn't South Park and what works for Matt & Trey might not work for Verronne & co. Futurama works when it's sentimental (Fry's Dog episode), scientific (the multiple universe episode), and character driven (Bender's new-robot episode). It hasn't been much of any of these lately.