It does the job (good/durable materials, very user-friendly), it's just that some more expensive ones made of elastic fabric fit better and are completely silent when dragged (not that this is bothersome, but it gives a 70s vibe, which you appreciate if you like disco). For external doors, prefer those. Inside the house (without air, that is) where you need many for all the rooms, these work just fine.

If there is a large gap under the door, in any case, you need to first use weatherstripping tape (on the bottom of the door, not on the floor) so that this can be placed underneath to completely seal the gap.

It can also be used on the top part of a crooked door that has a large and/or asymmetrical distance from the frame, just there it needs to be stabilized from above with flat pins. Weatherstripping tapes (or a combination of them) ranging from a few mm to 1-2cm may suffice for this application, but in some cases, the double Draft Guard is more effective because it hugs the door and both sides of the frame without creating resistance at the door-frame contact points.