They get better - but in the early game it can be rough. Flanking helps a lot (not necessarily behind them, just at 90 degree angles) but be careful moving forward too aggressively as you can "uncover" enemies who get a free move... and shoot you next turn!

I THINK one of the things altered in Enemy Within was encouraging a more aggressive playstyle (by incorporating materials that "blow up" after a set time) so I can't speak to how that alters tactics - good luck! Hope to see you around ;)

Not gonna start this, yet, as i still have to get Enemy Within and the rest of the DLC's. But once i grab them in a sale, definitely will play it. Also, i'm really looking forward to a Xenonauts sale to complete my X-Com/UFO collection.

Also looking forward to UFO2Extraterrestrials: Battle for Mercury. I've enjoyed the original way more than most of the UFO After games.

XCOM: EW is my favorite game of the past years. Love it!

And this mission... absolute gold! I was very fun the first time around when I did not know what to expect. Now it's easy.

I just did it in my "Army of Four" achievement playthrough (on Classic difficulty). I had mimetic skin on a sniper so I kept 3 people outside the ship at a distance, overwatch blasting everything that crawled out, went in invisible, started the timer when I was ready then got out invisible. With most of my team already out and the guy inside being able to safely dash outside, the timer was not really a problem.

Edit: For people who liked this game and want to spice things up check out the "Long War" mod for XCOM: EW.
You can get an idea of the mod over here: https://www.youtube.com/watch?v=zUeHJ2RU1e0&list=PLXctaw5JGF4L-AQIHCuAXI9orP85WnThc