I played BE and enjoyed it, but I ramped up to Apollo really quickly and was not very challenged.
I'm afraid to say that the Rising Tide expansion only succeeds in making the game
easier. The AI struggles to cope with aquatic gameplay and the wealth of new artefact bonuses and diplomatic traits will give knowledgeable human players a clear cut advantage.
I like Apollo difficulty compared to the previous build as the playing field feels a bit more level, but if you're after a Deity level of challenge then you're out of luck unless you play other humans.
The game felt very flat compared with all of the directions you could go in Civ V.
The only strategy you really had in vanilla Beyond Earth was to spam tile improvements in your cities, whether they were Academies or Biowells etc. Rising Tide is cool in that you have more paths towards victory now.
Al Falah, African Union and ARC have interesting playstyles for one and there are plenty of different diplomatic traits and agreements from which to draw crucial science and thus have a more unique game.
The cost per play time was FAR worse for BE than Civ V and it's expansions, does the BE expansion make up for it's cost?
I have to be honest: not really. Games were way too short before the expansion and they've only gotten even shorter now because of the new gameplay mechanics thus making the entire outer tier of technologies and their related buildings etc. even more unnecessary than they were before.
Has it had meaningful updates that did more than fix bugs?
Firaxis were pretty quick to adjust the war score system and a few crucial quest bugs, but things have since gone disappointingly quiet and several major problems remain unaddressed.
Several players' hall of fame database became corrupted somewhere down the line, multiple tile improvements can still be built anywhere without restriction and omniclast's exhaustive
bug list was all but ignored and he eventually stopped updating it.
Making matters worse is Firaxis' newfound tendency to try and fix things that aren't broken and thus screw them up completely.
In terms of tile improvements, arrays were made even worse by their move to Orbital Networks, Magrails now come later at Civil Support for some reason, and most of the advanced tile improvements take an absolute age to build now so you might as well just stick to farms.
Likewise, the Mind Flower and Beacon wonders have had extra turns bolted onto their activation thus making those victory conditions a lot more tedious than they were before.
They've also neutered Marvel quests completely by increasing the number of discoveries needed to finish them. With the play time being as short as it is already, I imagine many players like myself are simply ignoring Marvels altogether, which is a massive shame as they were intended to be a key new feature that added a bit of flavour to exploration.
Hope that helps.