I had a look at the Overwatch open beta. I found it fun and frustrating in roughly equal measure
On the fun side it looks wonderful, plays well, heroes are varied and most of them are really enjoyable to play with some great moves. The maps are all well thought out and suit the objectives (when players bother with them, not really happening in beta). Loot box cosmetics are a nice incentive system. It's all very polished, as you'd expect from a Blizz game. I love the fact that it's a FPS I can play without motion sickness (thanks to the good FOV and smooth graphics).
On the frustrating side, TTK is insanely fast and there's just too many cheesy one/two-shot moves in the game. I get that there's counters to most of the cheesy moves, but if your team lacks them then it means hero switching on respawn. Whilst this is an intended mechanic to counter team balance problems, it essentially makes gameplay glorified rock, paper, scissors (same old, same old). Perhaps it'll improve as players learn the game, but in noob PUG play the turret heroes are totally OP, I'm already tired of seeing "Play Of the Match <insert random name here> as Bastion".
It's nice to be able to dive into quick game when you just want 30 mins of mayhem. But overall gameplay is rather shallow and seems aimed at the attention deficient, so I'm not sure how much legs it has (for me) and if it's worth the asking price. If it were under ?20 I'd likely take a punt, but perhaps not at full price.
I suspect I'd enjoy Battleborn more (love the Borderlands games) but there's no trial of this available currently and given my potential for motion sickness it's too much risk at the ?39 asking price. Perhaps Steam will run a free weekend soon.