Ages ago, in an era of revolver & single stack semi-auto primacy, the P-35/BHP/GP/Hi-Power was the "It" gun if you wanted higher magazine capacity combined with an incredibly proven and reliable pistol. The gun got some 1970's publicity as it was depicted in the film Serpico and then later in 1980 as the weapon carried by UK SAS when they did the Princess Gate raid on the London Iranian Embassy. But the pistol was carried by armies all over the world for decades before that. UK forces issued it from WWII until just a few years ago. Even the Germans used it enthusiastically during WWII.
I've owned several over the years. They were all great guns. Back in the day (70's, 80's), I regarded them as mechanically reliable and durable as peer competitor Colt or USGI 1911's, HK P-7s, or Walther P-1s (P-38). I owned a MKII (stolen back in the 90's). During the 1980's, it fed most JHPs just fine and never had issues with +P (although that stuff wasn't as widely available back then). Back then, I carried mine loaded with Silvertips, Remington 115 gr JHP, and a few other loads. It fed them all, but liked the Remington stuff best (that load closely matching the ogive profile of 9mm ball).
I went through a UK SAS CQB course where we were issued P-35s and MP-5s firing identical 9mm ball ammo from UK NATO stocks. Those all-steel Brownings ate that stuff up and there was no mention by instructors about wear and tear problems. They (SAS CT Troop members) exhibited absolute confidence in the pistols and their durability with hotter ammo. They were pretty honest about most discussion topics and had no problem with lifting up their skirts to talk about other very real problems. But they didn't have any complaints about the Browning (other than ruefully admitting that they were getting old). NATO 9mm specs vary by country, but it's arguably always a bit on the higher pressure / velocity side... if not always into +P territory.
I CCW'ed that wayward MKII for several years (always cocked and locked) and regarded it as a reliable, durable, accurate, and tough gun. The design is dated, has a tiny safety, and the original military style fixed sights (or tangent sights) are a reflection of a different age. But that's fixable by adding modern combat sights. I've also found the Hi-Power to be one of the most elegantly slim and hand fitting designs ever created. The damn things just fit most people's hands really well. A common compliment given to CZ-75 variants is that they feel very similar in the hand to the Hi-Power. That accolade meant in a very positive way.
Like the military 1911A1, it's a dated design, but one which has withstood the test of time and proven itself in hard use. You've got a classic pistol which is still the equal of many more modern designs. Enjoy it.
Still makes my top 10 list for handguns to take to a fight.
Here's a How-To Pictorial for magazine disconnect removal: