Cons: None really, maybe a little bit linear
You play as the protagonist Link as he journeys through puzzle-filled dungeons to rescue the descendants of the Seven Sages and retrieve the stolen Triforce to restore balance to the world. While you do technically rescue Princess Zelda during your adventure, it's right at the start of the game and isn't really a big part of the plot. One big part of the game is the fact that you have both a light world and a dark world and eventually you are able to travel back and forth between them. Changing something (like flooding a corridor) in one world also affects the other world (allowing you to swim along that corridor to an otherwise unreachable ladder), which adds another element to the already bountiful puzzle aspect.
The world map is medium-sized, but there's an awful lot of content packed into it. Combine this with the dark world almost doubling the size of the adventure, and this game has quite a lot of gameplay and will require some time investment to complete. There are a lot of different enemies, from armored knights to big skeletons, snakes and slimes to cyclops and jellyfish, there's quite a diverse group of enemies to battle. These aren't just cosmetic differences either; one enemy may burrow up from underground while another may block your attacks with his shield. One may zip around the screen really fast while another might just sit and shoot fireballs.
You can look at much of the world map area from the start, but many areas are inaccessible for a while. There may be a gap you can't cross until you obtain the grappling hook item, or a boulder you can't pass until you obtain the gloves to lift it with. While this does help to keep you pointed in the right direction as far as game progression, it does make the game a little more linear as well.
The boss encounters in the various dungeons are equally as impressive and varied. Bosses usually take up like a quarter of the screen and are pretty mean looking, and they all fight very differently from each other. Usually they can sap quite a bit of your health very quickly, but they all have a pattern and/or weakness to exploit (often involving an item found in the dungeon) that makes the battle fun -- it's still challenging, but just the right amount.
The puzzles are pretty much a staple of Zelda games, and while there are a few that are frustrating and may leave you Googling for a walkthrough, most are balanced rather well. Blow a hole in the cracked wall here, go through and grab a key, go back up and pull a lever to flood the corridor, swim to the end and push a block down a hole, push that block onto a switch on the floor below to open a door above, etc. Overall very fun though, and it just wouldn't be a Zelda game without them.
There are lots of items to find as well and they all have their uses. Bombs, a bow and arrows, grappling hook, shovels, nets, mirrors... suffice it to say that you'll continue receiving new gameplay mechanics and puzzle-solving items throughout the game to keep things interesting. Some of the items you may remember from previous Zelda titles, but there are a lot of new ones as well -- the grappling hook in particular was a lot of fun.
The game looks beautiful -- the colorful graphics are very polished and animations are smooth all around. You can tell that Nintendo had a nice budget to work with while developing the game and took their time to do it right. In my opinion A Link to the Past is one of the better looking games on the SNES, especially the enormous dungeon bosses with their high level of care and detail. The music is mostly outstanding as well. A few tracks like Zelda's Lullaby are so great that they became classics and Nintendo pulled them into the later Nintendo 64 title, Ocarina of Time, where they continued to be fan favorites to a new generation of Zelda players.
Tight controls, countless hours of gameplay, unique boss encounters, beautiful presentation and a good story make A Link to the Past one of the must-have titles for the SNES. Being one of the best selling games on the system means that there were many copies produced, so you can still find it around today for $5-$8, which is an absolute steal. In fact, I would almost go so far as to say it's worth the price of picking up a $30 SNES console on eBay for this title alone.