The second reason I dislike the reduced effectiveness of prayer in pvm is because they are decreasing its effectiveness. I wouldn't mind in RuneScape gold the pvp world however, when you are unable to use protect prayers with 100% effectiveness, some bosses become a lot harder (and dungeoneering, see above). All prayer-boosting gear was also removed. This means that soul split and turmoil are more expensive and slows down the slayer if you don't use them.
Thirdly, I'm not a fan of certain of the decisions they made with regard to the weapon/armour systems. Shields are unable to track offensive statistics and I'm not sure what the defender's role is. Boots and gloves lose all offensive stats. All offensive increases are now relative, not absolute (e.g. +2% instead of similar to +8) and it seems that the only offensive factor that is able to be increased is critical hit chance. This can seriously damage weaker weapons, such as the rapier. Rapier's speed is lower than ever and is able to stab rather than slash.
That brings me to my next point. There isn't any style switching between melee and range. If you own a Rapier, you are restricted to slashing only and can only stab. If you want to use a slasher, you'll need to switch weapons. For distance, the only method to buy OSRS gold increase speed of attack is to choose a more powerful weapon. The only way to shoot farther is to choose an older weapon.