The most often said thing so far that I've read is that people are worried since the game is set in the north that it won't be that varied.
To me, Skyrim seems very similar to places we know like Iceland and such. Northern setting, mountainous region. However it's also a place of beauty and there is plenty of variety. It snows yes, but not always. There are t hings from forests, to valleys, to the snowy area's and of course, icefields, etc. You have area's of running water with grass you can see, waterfalls, and others that are frozen depending on the time of the season.
We already know lore-wise that Skyrim is varied as such, it's not just a 100% snow filled landscape with no variety, there's forests, fields, and many other things.
To give people an idea of what the environments "could" look lilke and the variety, here are two good videos I found showing off Iceland's countryside and landscape (I highly suggest watching in HD).
http://www.youtube.com/watch?v=fqfyH4H8pmA
Another video showing some more from the film, Beowulf and Grendel, which was shot in Iceland:
http://www.youtube.com/watch?v=K6IJ0Hz9XxU&hd=1
So that gives you a good visual picture of what Skyrim might look similar to, at least comparable to our world.
Now apart from what it may look like there's a few things, that to me at least, would really make this game stand out from other games.
The main thing, since the game will undoubtedly feature quite a bit of snow, is snow that has depth. IN most games of the past with snow you simply got nothing more then a "white" texture of the landlscape. There was no variety to it, just a white landscape and if you were lucky a "mush" snow sound effect at that.
One of the things that can greatly help this game not only visually standing out, but atmosphere wise as well to help immerse you into the world is if Beth goes a step further and has actual depth to their snow. Where different area's with more snowfall then others while also making it that more impactful.
One recent game that did snow like this SUPERBLY was Uncharted 2, the snow had depth that you would see Nathan actually trudge through and it also "stuck" to things such as his clothing and what not.
See video: (start at the 4:40 mark)
http://www.youtube.com/watch?v=NZPKnsfYC2o
HAving snow that looks and behaves like that in TES V would be a huge step up not only for an open world game but for environments in general. With snow being a major part of the landscape this would really help sell the atmosphere and setting of the game.
The next thing is Ice. Ice needs to well look like Ice. Being able to both allow light to pass through and reflect as well. Imagine at on epoint int he game walking through an Ice filled cave surround on all sides by melting ice, seeing your reflection in it and then looking ahead and seeing a blurred image shining through the Ice and not being able to tell exactly what it is.
These kinds of detail in The snow and ice could really help the environment out a ton, I really hope we just have a setting that is more then a simple flat-white texture as many games have relied on in the past.