Here's a link to look at just the new cards.
I've read some people who believe this is the most exciting Commander release ever but I'm not on board with that assessment. However, it does feel like the five decks are the most balanced of the releases they've had. No one deck or color looks like they have a significant edge over any of the others and they look like they will provide interesting games between those five decks. I like that. It difficult to design cards and build decks that match up so well!
Another thing that really sticks out for me is that there doesn't appear to be a Legacy or Vintage card, like True-Name Nemesis, Containment Priest or Toxic Deluge. As I said; the decks seem very balanced against one another. One possible exploit might be Seal of the Guildpact; anything that can make spells cheaper is always risky but at five mana, I doubt the card is going to make a huge splash.
Things I like: the Confluence cycle and execution. The use of Experience counters instead of a Command Zone reference, because Experience counters can be used in non-Commander formats. Myriad is a neat twist for multiplayer with cards costed at 1v1 prices. I'm told Two-Headed Giant is the format for the next pre-release; cards like Myriad could be really cool for people who like that style!
Thing I'm a bummed about: The 2014 product had some cool reprints from sets that didn't get a lot of traction and thus had cards that were difficult to find. Giving second chance to those cards and access for players who want them is a Good Thing. 2015 didn't really bring back anything unusual and I think that's unfortunate.
Thing I'm less enthusiastic about: The decks themselves don't seem to really monkey with the concepts of what the color pairings can do. U/G wants to talk counters (done twice now). B/G wants to talk graveyard (done forever). U/R is about spells, and that's been a thing since Zendikar. R/W wants to bring the aggro game into Commander-an archetype that's been around in Draft since Return to Ravnica at least. B/W is the most unusual one for me, with its enchantment theme. This was explored in the later part of Theros block and isn't something I've really seen in that color pairing much, so I think it's cool they gave it some room.
Still; my overall impression is good and I look forward to tinkering with these decks.