I absolutely LOVE this deck. I don't come from a RWS background but if you do, I'd encourage you to step out of your comfort zone ;-) because it's worthwhile (as I found when after many years I bought my first RWS). It's not totally different as far as card meanings are concerned - the approach is different.
The RWS gives you scenes like in a theater. It's easy to read in a narrative style with it, and that's great, it's a wonderful style and intuitive.
But the RWS doesn't usually challenge you to read abstract images. The Tabula Mundi, like the Thoth,is not a pip deck; there are strong differences in arrangement, composition, colour etc of the motifs, there are figures and animals... but there is no story in the minors that you could immediately latch on to. You have to interpret colours, shapes, composition, atmosphere, the whole scene with all its symbols - and that's intuitive reading, too. But non-narrative. Intuitive-abstract.
I'm sure that you can read this deck even if you don't have the astrological, kabbalistic and alchemical background its creator has. It's possible to read the Thoth perfectly fine just by working with the visual clues and basic knowledge of the tarot structure, I did it for years, and I'm sure it's great fun to do so with the TM. Yes, there are some minors with different meanings and some "intensified" majors but you'll get along.
But the best of all worlds is when the deck and its absolutely fantastic book start to draw you in. All this esoteric knowledge is like a wonderful wine whose mere smell makes you want to taste it.
After a while, you notice that you understand the Tree of Life and what decans are and the deck taught you.
That's what happened for me with the Thoth, I brought the (sparse) knowledge to the Tabula Mundi, and it's a joy.
I have the decan cards, too, they're such an intelligent, visually clever, stimulating idea.
The Tabula Mundi, more than any other deck I know, is built like a Wagner opera - not overlong and heavy and fulll of fat German tenors
but in its structure. There are leitmotif symbols that appear and echo and change through the deck. Like a net that pulls you in. It's not a collection of 78 individual cards, it's ONE complete, layered, tightly woven cloth. It's innovative in its fully-developed structure. It works like an organism.
I can't recommend this deck enough.
Card stock, art, creativity, presentation (beaaaauuuutiful box and additional stuff), and an outstanding book - no, this deck is a must-have.
For me, it's the deck of our generation. I'm sure this deck will be remembered as a milestone.
I love many decks and don't mean to put any other deck down. But M.M.Meleen set her aims very high, I can't imagine the scholarship and hard work that went into this deck - and achieved a deck that IMO looks eye to eye with the Thoth.
Everything you learn with it will benefit your RWS readings, too. The RWS goes nowhere, it's still there, you don't have to choose.
So why not go for it?
Sorry for my hyperbole, but that's how I feel about the Tabula Mundi.