Yep, I've been following Xenonauts since I backed the Kickstarter two years ago, and I'm extremely disappointed in the final release. Back even before the Kickstarter, there was an extremely solid and promising alpha demo, but unfortunately, the game hasn't really developed all that much past what was in that alpha.
As a fellow backer, I think the release of Enemy Unknown threw a bit of a wrench into my enthusiasm for Xenonauts in 2012, and after playing more than a dozen hours of the release version (keeping in mind that I've played almost 35 hours of the release version of Divinity despite it coming out weeks later) I'm not entirely sure how much more I'll play. It's well made and makes some smart tweaks to a 20-year-old game, but it's almost depressingly safe in its execution and its increased focus on the parts of old X-COM that I don't love (namely the air war) aren't doing much to encourage me.
Maybe making a shinier, more balanced (because why include fun weapons like Psionics and the Blaster Launcher?) but still faithful remake of UFO Defense was enough for me two years ago, but this entire thing hasn't gone above "comfort food" status for me. The Firaxis re-imagining, while not without its own flaws, at least is its own thing and is less slavishly devoted to recreating the good and bad parts of one of my favorite old games.