Hi Roisin,
I used Memsource (cloud) for a few months while working in-house and I liked it because it was very straight-forward and simple. It has far fewer options and bells and whistles (a.k.a. "things that can go wrong") than Trados, which I'm sure can be seen as an advantage or as a disadvantage. Personally I appreciated that very simplicity, but it's also true that I wasn't all that familiar with other CAT tools back then.
The only thing I disliked about it (although maybe that depends on your settings or the server or...) is that it insisted in suggesting machine translation options and that, of course, if the internet was patchy or gone, that was it...