Polypropylene is, IMO, the lowest resilience of all the main carpet fibres. Walk on it, it flattens, it doesn't "bounce" back up like a good wool carpet will. The carpet will crush more under furniture feet.
A correctly used good quality upright vacuum cleaner will delay the flattening process but not prevent it.
As time goes by, you will find that the flattened fibres/yarn will hold onto to small bits of fibre which you wont be able to vac out. Professional cleaning with suitable agitation will reduce this build up but not prevent it.
On the plus side, the yarn is cheap to produce so you get more carpet for your money. It's also very resistant to water based staining.
Other negatives are easily stained and soiled from oil whether animal, mineral or vegateable. Also it has a very low melting point. Drag a chair or table across the carpet and the friction can damage the fibre tips and sometimes cause pile reversal.
Safe and happy cleaning
Ken