I've stayed at the LHR Ren many times on weekends, either for mileage runs or to position myself for early morning return flight.
It's old & tired, but it's ok. I regard it like an old favorite bathrobe; a bit ragged around the edges but familiar & comfortable.
It's always cheaper than the Marriott, hence my decision to stay at Ren over Marriott since my stays there are on my dime. Like the Marriott, it's on the free bus route. It's good about early a.m. check in. Come January 7th, Golds & Plats will have free internet. Health club is small, but adequate. I don't think I've ever made it to brekkie, so can't address the restaurant. I know the lobby was renovated. It would be nice if they do the rooms, but there's nothing they can do about the size of them. The exec lounge is key accessible on weekends for water, tea, coffee, & as others have noted, it's got FABULOUS views of LHR & runways. I really like the cheese/fruit plate & wine they have as Plat amenity gift. As Glenn mentioned, it's a Cat 4.
For what it is, it's an ok choice for folk who want or need to stay near the airport. If someone wants Grosvenor House (and prices), they have that option in the city. For someone who needs a play to stay at a usually cheap price near the airport, it's certainly a viable option. FWIW - I don't usually expect fab things from airport properties, not just in LHR.
And to the OP - you have status 7 days/week; you just don't have a fully open exec lounge on the weekends. You're not 'losing' your status on the weekend
Cheers.