Concerned Parents: Read This
I am a seasoned user of IMVU, having been on the site for 7 years. As I've read through these reviews, it seems the main concerns can be broken down into 2 main categories: privacy, and sexual content.
Many other reviews touched on privacy concerns. There are no inherent privacy issues with IMVU, and how much information you share with people you chat with is entirely up to the user. It's always important to talk about privacy with your children and discuss what information is safe and appropriate to share with other users. In my time using the app, I have never once felt obligated to share any information, and even when people specifically asked if I wanted to cam chat, a simple "no" was all it took. If you're worried about someone pressuring your child into chatting over webcam applications like skype, or giving out their phone number, it will set your mind at ease to know that that is extremely uncommon, and simply educating your child on safe internet use will clear that up anyway. As I said before, there's nothing inherently unsafe about IMVU, and all private information is up to the user to share.
As for the sexual content, yes, many teens do use the site for ERP (erotic roleplay), but once again, this is the choice of the user. It's also worth mentioning that virtual goods used across the platform are suitable for general audiences, and even the items that straddle that border line are pretty tame. The more explicit sexual items and themes are locked behind a pay wall which IMVU calls their Access Pass, and you aren't obligated to buy it at any point in your usage of the platform. The Access Pass allows only adult-aged users to view, buy, and use sexually-themed items from the virtual catalog. In terms of virtual goods, you don't have much to worry about as IMVU has a strict guidelines about what is considered GA. Any virtual clothing for your avatar must meet a minimum coverage guideline that ensures that no avatar who doesn't own the Access Pass can ever be completely naked. As for rooms, furniture, and poses, you don't have much to worry about either. Some furniture items will feature poses for your avatar which load upon use, but those poses are also bound by GA guidelines, so the most you have to worry about are kissing poses.
As for sexual themes in conversations among users, it's pretty unavoidable. IMVU does not control what its users talk about, including swearing and sexual themes. However, not everyone using the site is using it for ERP or other similar activities, and it's even more uncommon among teens. You'll also be happy to know that IMVU is age-gated across the platform, and no adult users can seek out minors to engage with. Everyone 18+ has their own server, and everyone under-aged are on a protected server. Of course, there are always going to be people who lie about their age, so again, talk to your kids about internet safety.
All in all, IMVU is essentially just a chatting site where you can also make an avatar and explore 3D environments where you can interact with other users. It's like a sandbox, and how it's used is up to the user. As long as you talk to your children about safe practices when online, there should be no issues.
One last thing I would like to touch up on in this review is the virtual goods and currency. IMVU is free-to-play, so users can absolutely use the site for free if they chose. The money comes into play when users want to buy virtual items for their avatars or chat rooms. IMVU runs on a virtual currency called credits. $1 = 1,000 credits. With most items in the catalog costing around 300-800 credits, you can see how things get expensive pretty quickly. There are ways for users to earn free credits, but these tend to be a little unreliable and they don't always work or pay out. IMVU also has a few other upgrades for your account, which can be a little pricey, so keep that in mind.