If the Season 2 Pass only brings us Arms Race, I would be disappointed. The additional skill trees in the Designer's Cut for the vault hunters are wonderful additions, but are somewhat obsolete for current players, particularly for those who have completed the bulk of the missions. Arms Race itself does provide a new perspective though, focusing purely on gunplay rather than combining it with Vault Hunter skills and although it took me a couple of turns to get used to, I found it a great way to collect some great weapons. It does however provide for a replayable experience, each time entering the zone and discovering new areas before taking on the Heavyweight Harker. I am certainly hoping that the next phase of the Season 2 Pass will add another playable mission though.
If Arms Race is updated and improved, then I could see it being worthwhile, but if this is all it has to offer, then Designer's Cut feels like something that should have been a free update rather than an integral part of a new season pass.
Designer's Cut is a disappointing DLC that shows that even interesting ideas, if badly managed, don't automatically bring to success. Those who have already spent many hours in the cooperative mode will certainly be happy to spend more time in Arms Race or farm old bosses with new skills, but this does not delete out the questionable choices made in the first place.