I have two of the original Tides, and now a 2018 Tides I received as a gift in my system. Personally, I love the original Tides and still use them constantly. The new Tides has a lot of useful tricks up its sleeves that I haven't entirely explored yet, like being able to take four identical LFO's at different phases, or pan the same LFO across four different outputs, or clocking envelopes at four different speeds. The chords mode, is really pretty if you have a four channel mixer to mix it all down.
I'd suggest that if you're working with a small rack (or a rack that will stay small for a while), you may want to save up for the newer model. Don't get me wrong, the original Tides was maybe the third module I ever bought, and it was extremely useful even without all the bells and whistles that the new Tides has, but Tides 2018 will buy you some really cool functionality that you would need other modules for, especially when it comes to attenuating CV to the three waveshape inputs - that was my biggest frustration with the original Tides, and one of the reasons I had to buy an additional mixer/attenuation module.