Overall it was a good game at the time, offering many new features that other games lacked. But tons of bugs and poor implementation of some features makes this game inferior to more "modern" options such as the sequel 7.62 also available on Steam.
I remember playing this game several years ago, just before I got my copy of 7.62 High Calibre. I really like some of the features that Brigade E5 included, such as SPM and the weapons selection and customization. But the game was plagued with a lot of bugs that would make you want to pull your hair out. And even after all of these years, a lack of patches or bug fixes will have the game leaving a sour taste in your mouth.
If you like this style of game but want some "improvements", I would suggest you get 7.62 High Calibre and install the Blue Sun Mod (BSM) which includes the unofficial patch. That game offers newer graphics and better stability (mostly), newer UI and improvements to previous features, new weapons and locations, and a ton of other stuff.
Some of the biggest complaints that I have about Brigade E5:
1) When leaving items in the bank vault, for some reason any stacked items disappear. For example, if I have 5 boxes of M882 ammunition in the vault, coming back to the vault after a day or so of game time will cause the stack of 5 boxes to magically turn into one box. This tested same with magazines, armor, weapons, anything that was stacked.
2) Your weapons get dirty super-fast, to the point where it's simply ♥♥♥♥♥♥♥♥. For example, just moving from one map sector to another and your weapons can gather up 3-9% dirt. Even weapons that were stored in your backpack and have never been fired will still accumulate dirt rather fast. It's as if your characters are spending several hours a day intentionally crawling through mud and muck, and shoving dirt into their rucksacks for no good reason.
3) The bank system itself seems flawed, as your money frequently "gets stolen" when the bank is robbed. Doesn't matter if you had $5,000 or $500,000 in the bank, every few days it seems a robbery makes all that cash go poof. So while the thought of earning interest is tempting, the risk of losing it all makes it useless.
4) The lack of a centralized storage method means you'll often times be hauling tons of stuff to the opposite side of the map just to drop off equipment that you plan to save for future merc hires. And if you need to equip new gear for a specific mission, that still means a lot of walking. When combined with the above-mentioned vault bug, you're pretty much better off just selling everything you're not currently using and buying it when you do need it (if it's even available).
5) Enemies tend to spawn in or glitch through terrain, sometimes placing them in locations where they can shoot you easily yet you can't seem to hit them at all. Or enemies that "hide" inside of terrain making it impossible to hit them, but they can drop out and shoot you in the nuts when they're good and ready.
6) Hired mercs give absolutely zero warning when their contracts are about to end. You'll be marching down the road to your next mission objective when suddenly they say they're leaving, give you no time to extend their contract. At least in 7.62 HC the game will pause and a warning message pops up informing you that they'll be leaving in 24 hours, which gives you plenty of time to either extend their contract or at least drop them off in a location where they can be easily found later should you choose to rehire them.
I guess I could actually keep going on and on with bugs, flawed game mechanics, etc. And that's likely because I am fairly biased towards 7.62 HC after having played it for a while. My general opinion is that Brigade E5 was a decent game at the time, and showed a lot of potential. If you're a fan of 7.62 High Calibre already, or just a fan of the Jagged Alliance games, you should play at least a few hours of Brigade E5 even if solely as a means of education and novelty.
In regards to my recommendation to play the game, I'll say yes it's worth playing, even if just to see for yourself.