They could have done something interesting with this idea, something exaggerated and unlovely.
Recording novelty versions of pop songs is one thing, but saying that you're "extending the possibilities of the cello" by doing so is just cheeky. Luka Sulic and Stjepan Hauser extend the possibilities of the cello across 13 tracks, most of which will be familiar to anyone who has been listening to mainstream radio over the past few decades or so. Behold "Highway to Hell", "Candle in the Wind", "Clocks", "Voodoo People", etcetera. Track 11 is their own invention, "Orient Express", with the cellos being a train, chug chug.
The original songs are more reproduced than reworked, the original emphases are there, the tempo, the volume. Rihanna's voice in "We Found Love" is still her voice but now it's made of string and gliding around the landscape like a refugee from a Vivaldi number. They could have done something interesting with this idea, something exaggerated and unlovely -- acoustic hommages pushed to extremes, there's possibilities there -- but when technology come along like a butler to tamely help them out you give up all hope and realise that we're sticking with literal-minded fidelity instead. Trompe l'oeil.