I don't have a problem with Hillsong per se...but as with any denomination they haven't got everything right. I can't speak of Hillsong as I've never been there, but with the pentecostal movement in general I have problems with:
1) Prosperity Doctorine
2) Indulgence in the "gift of tongues"
3) Indulgence in the self
4) Indulgence of world things.
5) Incorrect notion of the gift of tongues and its relation to Baptism of the Spirit and Water Baptism.
I have to point out some pentecostal churches may not have any problems with the above, but I disagree with this notion of chasing after the gift of tongues. Not every Christian can speak in tongues, and the gift of tongues does not edify the body but the self. Certainly when I first became a Christian, it was at a pentecostal church, so I only speak of what I experienced there. But I came on Sunday's to "recharge" and to get on a high. It comes to a point when that was all a pack of lies. The gospel is not about me, nor is it about you, its about Christ. The whole concept or worship was wrong. Worship isn't just in song, or in speaking in tongues. Worship is something that our lives are meant to be. Every second, every moment - is meant to be worship.
Also at that particular pentecostal church the belief was held by some members (I don't know, as I never spoke to the pastor about it), by my friend told me that if water baptism, baptism by the spirit, and the gift of tongues occur at the same time. If you don't speak in tongues, then something's wrong. That is completely wrong, and it creates tension in the church, plus freaks out those who aren't Christians visiting the church.
The whole prosperity doctrine is scary. I don't know who from reading the bible one can get the notion that "By giving, God will give back to you" This was repeated everytime at tithing time. The gospels have nothing to do with worldly treasures. It is totally unscriptural. It digusts me that there are massive productions, constant pampering of how God has blessed the church. We are not blessed to be proud over it. We are blessed to bless others. There was never once talk of the homeless, or those living in poverty overseas. It was more "Look at us, God likes us, look at all our money and flashy shows" Church wasn't church - it was a show. And it wasn't real. People put on there Sunday selves there. What is the exact purpose of a massive church building with smoke, stage, lights, good equipment? I don't see how it glorifies God - Jesus never had flashy clothing or anything like that. Nor did Jesus ever indulge himself, and but excuse me, He's God. He could have and there would have been nothing wrong with it. Yet he doesn't, but people do? I must say however, there are wonderful Christians from the church.
Also the indulgence in the Spirit encourages followers to follow after the Spirit but fail to actually back anything with scripture. The tongues are not the be all and end all of the gospel - and it is presented as such. Knowledge of the gospels is second to indulging in these tongues. The whole gospel becomes one of experience - which is totally stupid. The gospel isn't about physical experience. The gospel is about how we are redeemed by Christ and how we are to focus on him constantly. I do wonder how many "Sunday Christians" went to that church.
That is not to say other churches are completely correct either, but they are very obvious things that is not correct with pentecostals. I must point out I'm not attacking the gift of tongues, or the Holy Spirit that would be blasphemy of the Spirit. But I use to think I can speak in tongues when I was at that church, but I now can assure you I don't.