As an arena player for years, this was a very welcome update. I love the new sets personally, and more than a few of them are very useful in their given ranges and slots. Its great to see the recipes added to the store for tokens instead of bought for gold like the others. I really like being able to use arena tokens to fund more arena gear.
That being said, my controversial opinion is that its a little rough needing 3 SE pieces per item and only 2 arena items respectively. Personally I'd rather see arena inventions use more arena tokens to invent. Really go nuts with rare and difficult extraction components. The potions are kinda the only token sink right now. I'd much rather be able to dump 100s of arena tokens into inventing arena sets. Not a huge deal, as this gives something to work towards and gives value to some SE drops I guess. It just feels like whoever gets them first might end up dominating certain brackets for a few months until they become more accessible.