First off, if you are going to watch or read it, make sure you watch the subbed ones. If you're honestly going to give a shot you have to be willing to put up with subs because dubbed is terrible. I used to watch dubbed and got up to about 100 something episodes in. Saw one subbed episode, went back and watched all 100 something again and the experience was so much better. The characters sound better, the story line makes more sense because stuff didn't need to be taken out so that western audiences wouldn't get lost, and scenes are more bloody and violent.
That said if you watch a lot of it all at once it tends to get a little bit repetative in the first few seasons where he recruites his crew. Some how every time they recruit a new member, they will verse an enemy crew who has a similar number of members with similar fighting style to them in either that or the next part in the story (eg. A swordsmen joins there crew, he fights a guy with swords. A sniper then joins their crew, 2 sagas later they're fighting a crew where one of the guy's shoots water like bullets). If you do stick with it though, the characters become very rewarding and very fleshed out with good back stories and quirks, even the little bit part characters.
Like you already said the fights are really interesting. The captains, first mates and the chefs fights especially are fun to watch because they're the strongest 3 in the crew and so their fights tend to be the most intense. The early season fights are good, but not as good. Things really get better by about episode 45, so if you can stick with it until then, it pays off.
Oh and be prepared for a lot of back story. While it helps to develope the characters and make you understand how they ended up like they are, almost every season will have 2 or 3 (in some cases more) episodes dedicated to telling a characters history. This does break pace a bit, but it helps later on.
One Piece is my favourite anime. Within arms reach I have the entire english released manga series, the entire released uncut series, and several figures. While I do love it, I know it's not everyones style of anime, so I told you what I feel are some of the irks I had with it. Hopefully I've helped.