Finished my first Stellaris run (base game only). Fun but it felt like it fizzled out a bit halfway through, when you aren't doing much more exploring (and so no more anomalies, so fewer little stories) and when all of your tech becomes a choice between +5% damage or +5% rate of fire. Got one end-game crisis (The Contingency) but by then a friendly Fallen empire had Awakened and did a pretty good job of killing the Contingency fleets even without me.

It was on pretty easy (no AI advantages), so I was super-dominate by the end -- that didn't help. The expansion packs look like they add some more end-game stuff (like more megastructures), so I picked those up on sale and will try another run (with higher difficulty) some day. Not for a while though.