I think ACM more than deserves some praise considering how hated and trashed it is by almost everybody.
Therein lies the problem. GBX did deliver a sub-par game. For up to 6 years many of us were expecting something a lot better than what was eventually on shelves. Pitchford took every opportunity to hype up this game and declare how dedicated he and his team were to the Project. None of that enthusiasm is present in the final product.
It's not just a few people that were disappointed by the end product. The overwhelming majority of Players canned it. Of course, being badged with 'ALIENS' themes, characters and situations is enough to keep some Players appeased. Good for you! You got a game you are happy with. The rest of us, however, who spend 6 years listening to Pitchford spin his fable were sorely disappointed upon the game's release.
It's not enough for a game to wear all the badges and trappings of its source material. It's got to deliver in other areas as well. 'A:CM's gameplay is no more sophisticated than 'Serious Sam'. For the most basic kind of FPS experience that 'Serious Sam' delivers, it's a better game than 'A:CM'.
If you enjoy the game, then that's a good thing. Somebody gets their enjoyment out of the title. Great! I'm happy for you but hHow much better could the experience for you be if the game was actually decent and praised by everyone else who bought it instead of just the relatively small number of follows that it actually has?
Pitchford still has a lot to answer for in the eyes of many fans. 'A:CM' could have been an absolutely Grand title. Instead it's a mess. It's exactly the kind of mess we don't need. We need more successful titles like 'ALIEN: Isolation'. No game is going to appease everyone but in achieving its goals 'A:I' was a much better gaming experience - and this is agreed on by most people who picked it up.
In the end, they are both very different games and will attract different players. As to which one is good and which one is not - that's a matter of personal preference.