I have had my Alien for a week today, great mod with just a few cons.
First con is the fire button was more solid the first day but has progressively gotten more loose. Now I can tap on the top and it is clicky, not even close on the first day. I did watch Daniels youtube video and know I can fix it but it doesn't bother me that much, I know it will bother others though.
The second con is fixable but when you select SS for TC the TCR is set to 105 which is for SS304. I do have a TCR table but don't remember the #'s off hand and was using the default TCR with SS316L. Of course TC was off and it wasn't until I investigated further did I realize I had to change the default SS TCR from 105 to 92. I do have a SS304 build on one of my tanks to use on my IPV5 so I put it on and it works great, I would say better than the IPV5. I did try a SS316L build with the correct TCR and it was nice but I liked the 304 setting so much I have been using that tank on there for the last 5 days, great vape.
I have read that the TCR for Ti is off as well, I don't use Ti so can't confirm though.
3rd con is it seems to go through batteries quick compared to my other dual 18650 mods. I have had to swap batteries on it everyday since I got it and I alternate between more mods than I care to admit. It is the only mod that needs a daily battery swap and I probably use my Hohm Wrecker G2's more which usually last me a couple of days.
Form factor wise I love the Alien, vape wise it is not going to replace my Hohm Tech mods but the G2 is not carry around friendly and the Slice is not as well built. I really am impressed with the Alien though, a big upgrade over the previous Smok mods.