I wouldn't say "every strategy is viable", though I feel a lot more of them are than in Vanilla.
Yield specialization is possible, but far less "take only one yield". For example, in the early game, I've remarked that I was actually generating MORE science by trying to be generalist than by trying to be specialized, because culture, production and faith give you so much yields trough policies/buildings/beliefs they are actually worth a lot of science. And I'm not even talking about unhappiness problems if you lack of one yield... [End game is different, as "science now" become much more important than "something that will eventually generate science"].
As for tall with poor lands: that's not really a problem. Just work specialists and Great Person Tiles Improvements. The only prerequisite to play tall is to have some food source (so oceans, or a lot of flat terrain to put adjacent farms) to feed your specialists, and an early production source (forest, hills, ...) to build your first buildings.