The tree scene was a weird moment, it provided the missing irreverent side of Yoda, but to the point of surreal self-satire (like was I watching new Star Wars or Spaceballs?). They basically just admit the force is a bunch of super thin BS they're either just re-recycling old dialogue for or making up as they go along, and that's why anyone can be a Jedi-like person or do anything one minute and nothing the next. So, while I did appreciate the underlying spirit of the scene (the Jedi are BS but that's not what matters), overall I didn't love or think it necessary for Yoda to show up and go all Reverend Lovejoy, "Luke, have you ever read this thing? Technically, we're not allowed to go to bathroom."
As for Luke... it's like they still never did figure out what to do with him. So, they kind of did nothing with him while trying to fulfill all our fan-tasies (bitter and maybe dark, grizzly teacher, Super Saiyan badass, full circle, or if you don't really want any of that, then he never left the couch!), but it amounted to treading water and just putting a cap on 30 years of... nothing. As rote and predictable as it would have been, they'd have been better off just having him show up at Starkiller Base in the third act of the last movie, or this one, since he still never showed up despite the cruel tease of his X-Wing (while we're recycling dialogue and moments and waiting for help, how about, "I'm Luke Skywalker, I'm here to rescue you!" coming in over the radio?). I'm seriously considering how one could edit these two movies together to make a better movie, basically tack fake Luke onto the end of TFA, which, again, are very Prequely thoughts. =)