I really do get more out of giving crits than receiving them. When you have to explain issues in detail so that someone else understands your reasoning, you have to make yourself understand it fully, too. If something's eh, you need to get at the bottom of why. Doing it repeatedly in others' makes it easier to tackle when it comes to your own writing.
Critting a good storyteller's book or pages is a joy, really, an even deeper learning experience. No book is perfect on the third or fourth draft, but you're wading through pretty thick stuff there. If something's not working, it comes off as a more vague sensation, like something's missing from a room you know very well, and you have to concentrate hard.
Critting is different than editing on a lot of levels. When I read slush, for one thing, I don't have time to explain to myself why something's not working. I just know it's not and move on. This is not to say I couldn't explain it if forced, I just don't owe that writer any particular explanations.
When going through final draft editing, I get to actually make changes right in the mss. We don't even use track changes; we assume the writer knows the work well enough to pick up on it and will let us know if the change doesn't work for them. The writer has the final say on how the mss reads. We have the final say on whether we buy it or not. It's an odd balance.
I'm beta reading a friend's newest book and I find some similarities in our voice. Very subtle stuff that I doubt anyone but he or I would ever notice. But there's times when I read where I can almost anticipate what's coming next, down to the word--not because he isn't writing fresh, imaginative stuff (it is, actually, very fresh) but because it's where I would go with it, too, given the character and the scene. It's not a right or wrong kind of thing, but more a kindred soul kind of thing. I've also found some distinct differences in style and for the first time, the differences don't make me question. They just are. It's given me greater insight into how I write and process scenes. Hopefully I'm being as much help to him as this beta read is for me.
And then there's writing. I wrote and sold a novella (details forthcoming) last spring with a partner. He plotted, I tweaked, and I did most of the drafting. He did final edits, which I further tweaked. Again, I think I took some directions he might not've but they worked--there was a lot of YES, that's it! in our emails.
It's all a funny game, isn't it, this writing gig.