Well, the area itself is like a learning zone since it's the first place you encounter the hand-balls in-game, and it's done pretty well when it comes to teaching the player how each of these enemies works. You first have the Gecko's in outside areas with lots of room so you can learn your way around how they detect and how they fight, and how you can kill them. Previously you've only encountered Gecko's in high-tension situations where you are in a hurry to get from point A to B fast, so you've mostly learned that they have serious firepower and maybe that they can deflect your missiles when fired from front. Next you encounter the handroids in a large, open room, where you can both learn that they can detect you via laser tripwires they set up, and that they attack in massive numbers, using both small firearms and special attacks against you. You can also learn that they have very large reinforcements, and that if you attack from a distant hiding position only the group you attacked reacts to the attack.
Next, you encounter two Geckos in tight closed spaces, one in a corridor and another in a large room with multiple obstacles. This is important because it helps you orient yourself towards how to evade, distract, or destroy Geckos later, and how Gecko patrol routine works in such an area. After this, you meed handdroids in a simlar environment where you have to navigate a more restricted area, with also more vertical placement for handroids.
This eventually leads up to the final room, which is a long hallway with numerous obstacles and both patrolling Geckos and handroids, and one of the toughest sneaking challenges to ghost through. A step up from this would have been to have human guards as well, but I think the area's strict adherance to its premise as UV enemies only in an abandoned facility works really well in itself so I don't feel that much was lost. As a sneaking area, it's definately the tightest design in MGS4.
It's also important that the player probably won't have a Barrett at hand, so they have limited ways of directly fighting Geckos.
I'd say that the game does succeed much more than any other game has attempted before or since in creating battlefield sneaking in several areas in prior Acts, in Act 1 it's fairly difficult to avoid battlefield conditions when you make your way along the road towards the abandoned hotel to meet Rat Patrol since PMC troops take cover in and move through the alleyways bordering the road, and the last segment is a small plaza with PMCs and rebels engaged in an open shoot-out involving a gunship that you have to cross either by sneaking, running for your life, or fighting through. In Act 2 there's a lot more parts where you don't have two opposing sides fighting and the power station is easy to just circle around, but the villa is a very good situation where you have to work through tightly cramped area with a perpetual combat between two sides. The villa also has more exploration offered if you go over every nook and cranny for goodies, but yea Act 2's areas between the initial ad hoc rescue mission you can pull to avoid hostile rebels later on and the villa are much weaker than in Act 1 due to having much more sparse enemy placement in a more open area (in Desert Level you have a lot more buildings with enemy sharpshooters and fire teams that make approach require more caution).
In MGSV I don't really get the same feeling or even attempt towards "battlefield infiltration", but rather a take at total tactical freedom.
(I played through MGS4 again with a fresh save two weeks ago, so it's in good memory)
PS: Confession, I always have more trouble taking out The Fury than taking out The End. And Laughing Octopus is the boss I have the hardest time with in MGS4.