I just bought a bunch of chests and keys (about ten). These were my thoughts:
1. They seemed to be strongly biased towards skins. I got one champion shard, and the rest were skin shards (with two ward skin shards).
2. Of the skins, two were legendaries. This seems like too much.
3. I got the Season Three Championchip ward. Was legacy content intended to be here?
Finally, I would really like it if there was a mass open button. It got repetitive.
EDIT: After opening some more chests and keys:
4. I got a rare gem. For the price of one chest + one key, I got... one chest + one key. Do they always drop that? Is there any benefit to getting these at all, or do they just waste my time?
5. The right side of the scree is empty more often than not when I am using it. This makes the whole interface seem kind of empty.