Nice picture! I love those old early cold war interceptors.
Some thoughts about this.

*delta wings were the darlings of early supersonic jet designers. They offer very low drag at SS speeds much like swept or stub wings, but can be rotated to high angles of attack for landing purposes without a ton of flaps and slats. Delts wings work well for interceptors and to an extent fighters, but the high landing AoA makes them poor for naval purposes. They also do not maneuver well because of the low wing loading. This is because there is a large surface area on the wing which bumps up drag at maneuvering speeds. The long fuselage also creates quite a lot of drag at high AoA.

* this design was an answer to the F-106 Delta Dart. Soviets tended to steal or emulate western designs at the time. The Fishbed was a rugged, cheap, simple aircraft used in a variety of roles.

* the nose is used as an inlet which is generally not a good idea. Out-front is best reserved for electronics. If you look through the early American jets you can see how they started with the same idea then gradually gave it up as the electronics increased. In contrast the Dart had split inlets located toward the mid-section which necessitated area rule techniques, but aft inlet locations are better. It looks to me as if this design had area ruling as well, which is a necessity due to the large mid-ship cross-section.

MiG 21 Wiki
Delta Dart wiki