I have two agency joiners and an agency labourer at the moment.
The labourer is OK - turns up on time and works. This is a rarity for agency labourers who are as often as not no-shows in my experience.
The joiners are a bit of a curates egg - good in parts. Neither has enough kit to do the job and always want stuff supplying - from an SDS drill to a circular saw - and neither have enough experience to do the job IMHO. With the agency premium they are an expensive option. They will be going when a couple of our regular subs become available
I have worked on agency myself at times in the past and this lack of toolkit and experience is not uncommon, although you do get exceptions to that from time to time.