Everybody wants to turn into a bear. Just imagine growing huge and getting sharp claws and ripping things up. Great, right? The problem is that game designers keep trying to put the turn into a bear experience into a game and it is always a disaster. Druids were a total mess in 3rd edition DnD with their ability to turn into animals that had the ludicrous Pounce ability and in 4th edition the druid, while reasonably balanced, didn't make any sense. You can turn into a bird! But you can't fly! What?
DnD Next is trying to keep the iconic druid ability to wildshape into all kind of things and it is looking like a real trainwreck. They aren't exactly repeating the mistakes of the past but rather coming up with all kinds of interesting new mistakes to make. The new idea about druid shapeshifting is that they will have a variety of forms and each of those forms will have its own stat block and a separate HP pool. Hooray for massive bookkeeping headaches! So druids are back to abusing the situation where they max their mental stats and trash their physicals since they can be a bear, but at least they aren't letting them just pick animals out of the book at random because that was a hilarious problem from day one.
I totally get the desire to turn into a bear. I love the concept of a shapeshifter in fiction. The trouble I have is that giving a character the ability to turn into whatever critter they want is always a disaster. This gives them the ability to fly, swim, echolocate, have incredible vision, smell, taste, and hearing. It means they are incredible scouts, potentially lethal combat machines, and maybe even able to communicate with creatures they otherwise couldn't communicate with. It is also obviously fantastic for hiding and sneaking. That is WAY too much stuff for a single ability to be able to accomplish, even if you set up the numbers such that turning into a bear isn't a free pass to kill everybody.
I feel like a far better implementation would be to give a shapeshifter the ability to shift into a single form. You could make that form fixed with specific benefits or allow the player to customize the form to some extent but as long as the list of abilities and benefits is set then the potential for abuse is very limited. For example, having a shapeshifter that can turn into a giant wolf which has a great sense of smell, fast movement, and decent unarmed combat would be a reasonable proposition. The Summoner in Pathfinder can customize their eidolon (a summoned demon) in this way and although the eidolon is a horrendous disaster numerically that general idea of customizing a form is pretty cool.
Switching in between two forms is a bit of work but not too much I think. The thing you really need to avoid is people flipping through the Monster Manual or nature documentaries looking for ways to make their shapeshifter even more flexible and annoying than before.