Honestly it's hard to not recommend a small DLC such as this, but 1.5 robes out of three here are redundant and act more as debuffs than actually changing how one plays in an engaging manner. Magicka deserves praise, so this is recommended but just know what you're buying.
The most egregious one is the Support Robe. Your staff, while it increases ally spellcasting capabilities, weakens yours significantly. Oh, it also increases enemy damage. Essentially the only gameplay modification is that you have to be closer or farther to whatever you're trying to assist. But your spells function the same, just much more weakly and much less usefully. It's a passive gameplay change that has significant active gameplay deficits; it's really not worth your time unless you're dedicated to the appearance or you're willing to pay an altruistic cost at absolutely no benefit to yourself. Essentially, the starting equipment is worse than even the default items, because your typical blunted sword is replaced with a simple punch. That's it. That's all it is. It does minimal damage. You lose out on everything, and gain very little active gameplay benefits in return. Obviously you can swap out your weapons as you go along in the game, but then it makes the existence of the robe/class redundant if they're not worth it at all. And, unlike the other classes in this DLC, it has no differentiations besides equipment from the default robes.
The tank is somewhat less egregious. It too, gives up spellcasting capabilities in order to promote tremendous survivability. You're quite slow, but you'd think that they'd make it up by giving its melee weapon at least something to compensate the low spellcasting utility (and damage) that it trades for its durabilityand speed, right? Not at all; in fact the blade is even worse than the default one, despite looking much more thematic. Again, you can swap your weapon out for it but it continues to make the class somewhat redundant. That being said, this one actually has built in traits that make the Robe/class unique. The support does not.
The Rogue is actually one of the most fun classes yet. It not only has a major active change in gameplay, it also has weapons that both compliment the rogue's gameplay and even enhances it. Instead of a sword, you get a crossbow that inflicts poison damage. Instead of 1000 base health, you have 400, but you move dramatically faster. Your staff is smoke bombs, and you can blink across the battlefield for a high-risk high-reward gameplay style. While it's very easily one shotted by stray attacks, it's capable of surviving on its own too. Playing this one, then playing another one of these classes just leaves a sour taste in one's mouth because the others are so lackluster by comparison.
So really, it's up to you if you think 1.5 decent robes are worth it. Honestly it's not too bad of a price but it is pretty nickle and dimey. It's just a shame the support robes are pretty pathetic in function.