Here's the thing, like many, Luke was one of, if not my favorite character. And like many, on first watch, I hated what they did. On second watch, I changed my mind. Yesterday was the first time I watched it at home instead of the theater, and found myself really appreciating what Johnson did.
Luke develops from a bitter old man who feels like he let the universe down, to a man who realizes he's been wallowing in self-pity and redeems himself and becomes a hero again, even showing just how strong (more than anyone else who we've seen) in the force he really is at the end with his iconic appearance. He ends up being the spark that drives a renewed upsurge (I assume) in the force and the rebellion.
The only thing I didn't like (aside from Super Leia, which is ridiculous) is Luke's flippant toss of the lightsaber at the beginning. If that particular move was cut, and he instead gave it back to Rey, I think it would have set a better tone from the outset.
Trust me, I am a Luke fanboy who wanted him to be the Luke of old. But by the time we got to the end, the Luke I've always known was once again there to save the day. And to be honest, I think Luke will have a critical role in the next film, as he will train Rey as a force ghost. I am guessing, but I do think there is more to Luke's story.