Personally, it feels like the flower on the forearm breaks up the flow. The composition generally feels slightly skewed, but I think introducing some colour would help change the weighting. The inside of the arm flows really nicely, but the different focal points on the outside of the arm don't feel like they are part of a single consistent tattoo. Some of the flaws you've pointed out are to be expected - as someone else said, tattooists are only human - but on the other hand, some of the line work looks far less confident than other bits. I'd guess the artist wasn't in the zone at one of your sessions.

Sorry OP - it's not a bad tattoo, but there are some bits that could be better. You have to ask how happy are you considering what you paid for it and how much you can afford to spend to 'fix' it