I've been playing through the game since Saturday and I'm not done yet (so I won't be opening any spoiler tags) but I have been finding the whole experience ridiculously enjoyable. I've been reading some comments here and other places, as well as thinking to myself about the experience of this game compared to previous titles, and I feel like I'm far enough so that I can weight in a bit.
There are sort of three broad categories that concerned or intrigued me: non-linear gameplay, the item rental/purchase system, and the unified magic meter governing item use. They are all quite related when you think about it, but of the three, I'd say I was the most skeptical of the rental system. It's really great to be able to explore wherever you want and stumble across any dungeon not knowing what awaits you, but some of that exploration factor IS a little diminished by the fact that you can deck yourself out and set off knowing that (almost) nothing is out of your reach. There's something exhilarating about settings off to explore with a newly procured item, testing the limits of your gear in those new wilds and uncovering those extra secrets that were just out of your grasp before, but which now you can conquer. Similarly it was a sense of achievement to finally reach that new dungeon, knowing its precious treasure will soon be yours once you outwit its clever tricks.
Some of that has been certainly sacrificed, now that you can waltz in and scoop up the entire inventory in one fell swoop. Which is exactly what I did – I had more than enough cash on hand to rent everything in the store as soon as I was allowed to, since rupees are quite abundant. It's true that it creates a bit more tension since you lose the items upon death (until you permanently buy them), but save points are everywhere. However, this sacrifice is basically countered by the fact that you've got a massive world to explore (well, worlds), and there are just so many ways you could go and areas to brave. I'd forgotten how cool that feeling is. The reassuring thing to top this all off is that there are still items that you can't straight up rent. Some of them are more minor, or optional, or upgrades, but all of them help in some way, ranging from letting you win heart pieces to actually being required to access different areas. So the sense of restriction is not totally lost. There's still that feeling of "man I can't wait until I figure out how to get over there!" Just not as much. And I'm really glad there are so many missable items! It makes me feel really good when I diverge from the main story to look around and I find bottles, or Pegasus Boots, or other such things.
Other than that there is little given up for the open-ended order and exploration. Normally there is a trade-off between a tight narrative or open-ended gameplay, but this is a Zelda game we're talking about here. There isn't exactly a reason to restrict the player for the purpose of a strong story progression. So I would say nothing is lost there. I do slightly question the choice to reveal the entire world map to you from the get-go, as opposed to filling in gradually as you explore new areas. That's one thing I would have appreciated. I also personally would prefer that my map not be marked with an X at all the locations I'm supposed to go. I try to ignore it and immerse myself in the exploration factor.
I thought the inability to run out of bombs and arrows would bother me, but it hardly does. Really when you think about it, running out of those things is just an annoyance that forces you to go restock. It doesn't really add anything, nor make things harder, unless you wander into a dungeon that requires them without enough – which goes back to the annoyance statement. There's a slight sense of accomplishment when you blow up a cave entrance or something and think to yourself "Hah! Did you really expect me not to have my trusty bombs?" but really that's minor. Moreover, now they've restricted you from spamming the things left and right by making them consume magic, so that's probably even a positive thing. Although I am still slightly bothered that I can run out of meter just from say, firing my Hookshot one too many times.
Overall I don't see any real downsides anywhere in the game. People keep saying the game is easy, but unless you're comparing to Zelda 1 or 2, I'm not even sure how that's a new development. No Zelda since then has been hard. The closest thing to something challenging since those early days, for me, comes in terms of puzzle challenge, not "I'm going to die" challenge, and I would probably cite the Jabu Jabu dungeon in Oracle of Ages. So far in Link Between Worlds I've found quite a few very clever puzzle mechanics, sometimes for optional items or even in optional locations (like in treasure hunter caves), and it's impressed me. They really managed to keep things fresh, especially with the spacial manipulation that becomes possible in painting form and taking full advantage of the Z axis (height).
I also don't think the game is short when you consider what you're getting. A lot of the fluff that comes with most of these games has been distilled out. Things like (required) fetch quests are all but non-existent, and they wouldn't even be tedious given that there are so many warp points in the game and you get access to them quite early. So if some gameplay time was reduced there, it is probably largely due to not having to haul your ass across the map for 15 minutes every time you want to go back and forth between locations. I feel like they've distilled the experience into the core of what really matters, and separated out what some people find boring or tedious into sidequests. There are plenty of mini-games if that's what you want, plenty of secrets or puzzles that just net you rupees (and sometimes heart pieces), plenty of little rewards off the beaten path. In fact, if you're anything like me and are obsessed with scouring every inch of every new area you find, then it probably makes the game even longer. Why? Because there are tons of places you can visit early on that don't have much to do in them until a later point. And then there's the maimais. You can totally ignore them, but I love finding them, and seeing the effects on my items (is it silly that I almost care more how the icon will change than about the actual effect change?). Incidentally it drives me crazy when I hear one under a boulder but still have no means to destroy it.
Anyway, everything is enhanced by the ridiculously good music, a mix of new, old and older, and the copious nods and references to past games. It makes everything such a joy. And if you stop and think about things, sometimes there is more hidden meaning than it would seem! Or, in the case of the example I'm about to give, if you stop and think AND know Japanese. Did anyone notice how bees are for sale at the shop for 888 rupees? That's an odd number, isn't it? Well, in Japanese, the word for 8 is "hachi." Incidentally, the word for "bee" is also "hachi." THE MORE YOU KNOW!