I thought it was fun. Never really knew exactly where it was going until the last episode, where admittedly I saw a lot of the twists coming. The very last scene also doesn't make a lot of sense. So from a plot perspective, the ending is kind of meh, but the action is really fun and exciting and, for me at least, made up for the slight dip in plot.
I thought that the main characters were a good mix of likeable but flawed. The whole season is basically just someone trying to assemble a team of people that are too wrapped up in their day to day lives to care. I can see why that might get on some people's nerves, but I found it funny and very realistic for London. And their personal lives are plenty entertaining and somewhat relatable...albeit a bit over the top.
Occasional subpar acting, but a lot of really good acting and quite memorable moments and characters. Villains are pretty cliché, and you don't get much out of them, but I could definitely get behind a season 2.