First let me say congrats on your release of the first 5 chapters... A lot of work went into this no doubt.

Generally speaking I enjoyed playing your mod but also find it unfortunately very lacklustre, the way the whole mod has been constructed thus far.

Below I'm giving you insights as to why I feel that way.

Intro: Wasn't so bad actually with exception of those 2 grunts standing there like they are standing on flat ground. Perhaps create some poses for them so that the leader holds his hand onto something up the top.

The guy standing against the wall shouldn't be there at all not sure. Visually the Intro was rather well made except for the very unrealistic Osprey Interior. Even the Gearbox hl1 version looked better. Improve upon that. Make it slightly smaller in size and it'll look great.

While the chatter is a nice resemblance towards Opposing Force I feel that custom voice acting giving you your current objective would serve better. Even a simple text message would suffice here.

1st map:

The rappelling had a nice touch to it but should possibly happen immediately considering the player lacks a proper animation and so it seemed for your fellow soldiers.

This landing area was possibly the most polished area of the entire mod. I enjoyed it immensely though the sun could be a little less bright.

Npcs: The way your soldiers are following their waypoints is terribly made.
A. Why are they all running towards a single spot less than 1 meter apart of one another?
Put some more effort into it like you did on some later spots of the mod. Let some of them kneel let some look north, west and so on simulating a sort of awareness and spot covering.

B. I often noticed that they love to look against walls and cliffs. It simply kills the immersion. You can control where they look by changing the angular of said WP Entity.

Throughout the mod:

While I realize that this is just a 1st release and more a beta than a finished mod I urge you to continue adding more scripted events. The whole mod feels rather monotone and static at the moment. Soldiers just standing there.. Few executions here and there simply won't cut it to recreate the feeling Black Mesa brought us. How about few Earth Quakes inside the facility. Anything to add more atmosphere to it what brings me to the next point.

Mapping:

Clearly you must be a former Gold Source mapper I noticed so many similarities to Gold Source mapping, not good. Most corridors appear either huge, empty looking or like a chunk of hastily put together room blocks. Whenever a player feels and see's that it's not a good sign for the mod. My advice continue improving upon the rooms. Add more rounded up structures.
Simply put think outside the "box". Also the Landmarks require some additional work. In some maps you're suddenly like 10 meters elsewhere after a map change. It was confusing to say the least.

Textures: Sometimes very good, sometimes very simple and ugly looking. Perhaps recheck some of the original Black Mesa maps to get some ideas which texture combos might work best. I often had problems myself to find the right texture set. So I know that it isn't an easy thing to get done right.

Now I know this is a lot of negative criticism but I rather be honest than a liar. Besides I think honest criticism is more worth than 1000 people just saying "awesome". Keep working on it keep improving on it.

Scenes such as the Gordon Freeman crossover are just the thing to make your mod epic. More of this.

I think this mod did good audio wise. At least there was always something to hear most of the time.

Conclusion: Right now the player is somewhat lost as what to do. Why we all know Half-Life and know exactly what our task is I still feel that the player needs a general purpose other than kicking BMRF staff and some nasty Alien asses. Why not let the player attempt to reach a certain radar or satellite dome, or missile silo etc. Trying to disable or destroy it etc. Improve upon the mapping and texture choices and most importantly bring the facility to life by adding various cool npc scenes which gives the player ice cold chills while playing. Try to get some simple story elements into your mod. Do that and your mod has the potential to become a top mod for Black Mesa. Please don't be discouraged but get rather filled with motivation and inspiration to do better. I'm looking forward to your next chapters.

Mapping: 3 of 5
Architecture: 2 of 5
Scripted sequences: 2 of 5
Audio: 4 of 5
Score: 11 out of 20 points.