A decent though outdated game of golf.
Swinging the club involves the old-fashioned (some would say "classic") three-click swing method, same as before. The gameplay is exactly the same as HSG3, with a few extra gimmicks like different clubs and the "Full Power Shot" thrown in.
The graphics are what you would expect from the series. The courses are rendered nicely, though unspectacularly. The golfers look okay in a cartoony sort of way. The spectators in the tournament mode look hideous. But then, that's not such a big deal.
In true Hot Shots form, most of the sounds, music, and character voices are thoroughly annoying. The music wouldn't be so bad if it changed hole-by-hole, but nope, you get the same track for an entire course. There are a few good caddies, but most are horribly irritating. So are most of the game's characters, although (fortunately) your character won't be talking a whole lot.
As said before, HSG4 is more of an expansion pack than anything else. With a few minor tweaks to the graphics, a thouroughly average roster of new characters, and virtually no change in gameplay, it seems clear that the overwhelming majority of development time spent on this game was given to creating six new courses, in addition to the six from HSG3 which return. It actually works pretty well - although some of the courses feel a little contrived, some of the more fun thematic ones are a blast to look at and play, and offer a greater challenge than the HSG series normally provides.
Because of the additional courses, HSG4 is deeper than its predecessor, and so if you don't already own HSG3, or haven't played it in a good long time, HSG4 might be worth a purchase. Just rent it first.