I haven't worked with them, but I have worked with similar agencies. Based on my experience with them, I wouldn't work on reviews. These agencies have a job to do, and that is to get people into work. Like it or lump it, that is what they are being paid to do. If you want to find work and engage well with the opportunities available then you will more often than not succeed, and so you will be happy (and happy people often don't write reviews). If you have been sent there and finding work isn't on your agenda, then you will be grumpy, very unhappy and refuse to work well with them. So yes, you will write reviews about things like them trying to force you to work!
Like I said, that is based on my experience of a lot of agencies exactly like this. So I'd say that if finding work is something you want to do, and you are realistic about your options for employment (another factor to consider - if you have few skills or qualifications then prime well paying jobs may not be on the agenda - but improving those things might be!) then my experience of about a dozen similar places is that they work well for people.
To be fair, agencies like this hate having referrals from people who don't want to work (although the DWP don't care about that!) because they can put a lot of effort into the trying to help them, but they get little or no payment at all for that. Also, it is normal for people to have to sustain work for a specific period of time - often at least 6 months - for them to get the bulk of the money. So there is no advantage to them in forcing people into jobs that they won't stay at.