I used them last summer: in the car so cannot comment on how they deal with bikes. My son lives in Portsmouth so that was a big factor in choosing them.
If you want a cabin then book very early: there aren't many to go around.
The seats in the lounge are okay and they don't seem to mind people taking on sleeping bags and kipping on the floor.
They take a very long time to load the ship: they use suspended floors and there's a lot of faffing about with hydraulic ramps. We were on one of the top floors so had to wait for the lower deck to be emptied before being let off the boat. I imagine bikes would be on the lower deck anyway, filling in the gaps too small for cars at the pointy end. The ship arrived on time which is the important bit really.
On board catering is expensive but as the boat leaves very late from Portsmouth you can get a meal before you board. Likewise, get breakfast in France: it will be nicer and cheaper.
On board facilities are minimal: there is a very small kids play area inthe corner of the main lounge. It gets very noisy on the return crossing. I've no idea if club class is better.
Compared to BF the service is inferior. There again, you would expect it as there is a huge price differential.
If I had to collect the sprog from Portsmouth or was heading to Western France then I'd certainly use them again. However, if I was travelling solo on the bike to the south or east then I'd probably zip down to Dover or the Tunnel and get a crossing late afternoon and stop in a McHotel in somewhere like Arras or Cambrai. I think this would be more peaceful and maybe cheaper.