I would not say the above is wrong but it misleads.This wasn't a criticism of the train service in Gunma. The OP asked what transportation people in Gunma use for daily life, and as far as I'm aware from my experience in Gunma/research, and from what I've heard from people living in Gunma, most people tend to drive. I will admit that I don't have much experience with travelling in Gunma, as I've only been there twice, but I lived in the Utsunomiya area in neighbouring Tochigi Prefecture for 8 months, where almost all the locals drive, and most people claim that Gunma is even more car-centric. This is not just the opinion of a few people, Gunma and Northern Kanto in general are generally considered Kuruma-shakai (car-based societies).
When I said Northern Kanto's cities are designed for cars, I meant that shopping/dining/entertainment facilities aren't exclusively centred around train stations or city centres, many of them are spread out along long roads, with large parking areas, or in malls outside of the city centre, although the malls often have free shuttle bus services.
We have Tobu-line (every 20-30min), JR lines (every 15-30min) and bus services (I don't know I don't use).First, frequency isn't the only factor to consider if you're going to judge how ideal a city is for pedestrians. You would also need to consider how much of the city is covered by public transportation, and whether or not shops are concentrated in one central area. I'm not going to make any judgements about how ideal Gunma is for non-drivers, but my impression is that it is more car-centric than Saitama and Chiba prefecture's most heavily populated areas. This wasn't what the OP was asking though, so there's no reason to discuss this in detail.
Second, as the OP hasn't mentioned the area where they will be living, this could be misleading too. To be more accurate, train service varies by train line, rather than the city. The Takasaki and Ryomo lines both have good service, but the Joetsu and Shinetsu lines have 1 train an hour, and 2-3 an hour during peak times.
I have not seen unmanned staitons around Gunma yet, but accroding to my experience in the other places, ususally there is a ticket gate nowadays, which you can scan your IC card as well as the central Tokyo.This is a very minor detail, but there definitely are unmanned stations in Gunma that don't accept suica cards. I looked into it, and I found a list of train lines that don't accept suica at
http://blog.livedoor.jp/sashibuxxx_osaka/archives/51962881.html. Suica isn't accepted at stations on segments of 2 JR lines, and on 3 private rail lines. I once stayed close to one of these unmanned stations, but it was in a very remote area, so the OP is very unlikely to encounter these in their daily life.
You had better understand that Gunma is within Shutoken(Metropolitan area)Although Shutoken is one of multiple definitions of the Tokyo area that can be referred to as the Tokyo Metropolitan area in English, Shutoken is the widest definition that includes the entire Kanto region and Yamanashi. This definition is based on administrative boundaries, and includes many non-urban areas in Northern Gunma and Tochigi prefectures, as well as the Utsunomiya area, which as a separate, smaller metropolitan area. Other definitions of Tokyo's urban area includes Maebashi, but not cities in Northern Gunma. It is incorrect to say that Gunma is entirely rural (which no one in this thread has claimed), but it certainly includes several rural and remote areas. The OP may very well end up in an urban area with good transportation links, but as they have asked for information about Gunma without stating a specific location, all we can do is make assumptions or an overview.