I use those type of e-cigs. They are discreet and fairly cheap to run; you can usually pop the cap off the top of the cartridges and refill them up to 10 times. After a while they start to degrade, so will start to taste burnt and nasty, and might leak, so that's time to use a new cartridge. They are quite pricey if you throw away the empty cartridges each time, you'll get through 1 a day I expect. The claim that "one refill = 20 cigs" is fairly accurate, but it's not based on the number of puffs. With an e-cig you can just have a few puffs at a time, when obviously with a real cig you're mostly going to be smoking the whole thing at once.
The battery is also small, so expect to charge it at least once a day. Mine is only 180 mAh and I charge it 2 or 3 times a day.
For £58 though I'd expect it to come with at least 25 refills. That looks very pricey. The cheapo ones I buy from the local hardware store are £7.99 for 5 refills. The battery and charger pack (and 2 refills) was also £7.99. I hope you get on well with them, but to be honest I would not pay that price for them again. That charger looks identical to my old one which ceased to work after 6 months. The cheaper ones are virtually identical.
Most people who vape will recommend upgrading to the pen style ones, and then to the "mods" which belt out massive plumes of vapour. They are extremely nice but very expensive to run. Plus they are not discreet at all. The pen style ones I have tried 3 different types and did not get on with any. So if your little e-cig suits you, I'd stick with it, and remember to buy your own e-liquid and refill as many times as you can and you'll save a lot more money.
I have no cravings for real cigs now, but of course I'm still consuming nicotine. Mentally, I'm still an addict and I hate it.