As a fan of the original movies I was expecting far better of this instalment than it managed to deliver. It felt a much smaller film than its predecessors and some of the visual effects, especially during the initial action scenes, had some pretty appalling chromakeying and compositing, ruining any sense of realism before it even hit its stride. As far as story goes, this film has one upon which it can hang an excuse for some violence, and that's about all one can say - but it's an Expendables movie, so I doubt anybody would go in expecting a deep exploration of the human condition.
The whole thing felt lacklustre, and certainly doesn't do credit to the actors (those choosing to sit out this instalment dodged the proverbial bullet). Maybe these issues are the result of the pandemic related delays and presumably restrictions the film suffered, though I've seen plenty of movies filmed during that period which still managed to maintain a higher quality, so something was definitely off about the production on this one.
If it turns up on TV and you like the genre then, sure, it's not a complete waste of your time, but I'd certainly think twice about paying to sit through it.