On PS4? It's all dependant, really. @Mr\-Paul may be good people to answer the question though as they've gotten into it more recently. I wouldn't have judged Eenuh's performance last night as bad at all; but that could also relate to the role/character being played. Not saying that in any way as a judgement to Eenuh, mind! Mercy's a good character to get into as a beginner(and useful, and underplayed by others imo) and you'll still keep learning as time goes on and you get used to more of the game's mechanics etc. I find your timings on certain things can tighten up, if that makes sense.
The one good thing - there's no 'time advantage' to having played the game other than simply being a bit more experienced. Even high level players, as many of us seem to encounter, can be absolute fucking idiots. Hell...I'm like level 130 or something and I know I've still got massive gaps in my playstyles.
Despite that - I've played 80+ hours already checking my stats. Every time I think about my gaming time at the moment - I think about Overwatch. It's a game you might have a 'quick game' on but end up on for a while. It's better with company, but still enjoyable without.
Ofc, there's no real single player so it's all online multiplayer, but I think with picking 6/22ish heroes per match for your team, against 6/22 heroes on the other team, and how people play all those different characters and how the interactions go - the level of variety is potentially huge although sometimes maybe subtle(obvious strategies and plays evolve for certain characters but, as with any game like this, the meta slowly evolves too). They're still releasing content too. We just got a new character like a week or two ago. We got a new map. We got new modes.
I think there's certain characters that are easier or harder to 'git gud' with; but I also think that's depending on you. I see people play some of my favourite characters worse than me, but they kick the shit out of ability with my less favoured characters. Sometimes there's factors out of your control that are frustrating(teammate choices etc) but again that's something that can be negated by playing with other people. I play fairly regularly with 4 of my mates, and then you've got all the N-E folks here too. I'm always happy for folks to jump in with folks and I've had some really nice sessions with Emerald Emblem on occasion.
I'm obviously very much in love with this game. Sure, there's a chance it might not be the sort of game for you, but I think with it going for £25-30 reportedly atm that you should take a chance and get it for yourself as an early present now :p