I have done both the Wishes Fireworks Cruise and the Illuminations Fireworks Cruise. To help you understand the opinions I'm about to express, I am an avid fan of the Magic Kingdom (it's my favorite park), and I LOVE Wishes! While I enjoy EPCOT, I have never been a fan of or felt truly appreciative of Illuminations. For some reason it never had that same "magic" to me.
That being said, I did enjoy the Wishes Fireworks Cruise. However, I personally enjoyed cruising around in the boat on the lake far more than the actual fireworks which were not nearly as impressive from the boat as they are when watching from inside the park in front of the Castle. I truly believe I saw a similar perspective of the Wishes fireworks when I dined at Ohana where they pipe in the music once the show begins. While I enjoyed the Wishes cruise, I can't say that it's worth the cost. In fact, I think I had a much better time at the Wishes Dessert Party which is a huge cost savings - by hundreds of dollars!
However, the Illuminations Fireworks Cruise is a different story. Although Illuminations was not my favorite Disney experience by any means, the boat parked so close to the action that it actually shook with the vibrations. To be so close, yet safely situated took the entire experience up several notches. Additionally, because of where the boats park for Illuminations, we had a clear view of everything. It was literally a front row seat, where as the Wishes fireworks cruise was like watching from the last row in an enormous arena. This fireworks cruise alone changed my whole opinion of Illuminations.
To sum it up: Would I do another fireworks cruise? Yes - but ONLY if it's Illuminations. Otherwise, the Wishes cruise I would say is not worth the price tag. Hope this helps