I took the bike into the mountains of north east Victoria on the weekend and went riding with my nephew who was on a tricked out Honda CR250 motocross bike. Not only was he 40 years younger, he also knew the trails like the back of his hand, and it's been a while since I've ridden a motorbike off road.
However I was able to keep up with him pretty well the entire ride and he had to keep checking where I was as he couldn't hear me coming up behind him

Although he had 3 times the power of my bike I was impressed how hard I could go especially on tight rocky trails. No hill was too steep to climb, you just lost traction or couldn't hold the front wheel down.
A bit more time on the dirt, fiddle with the settings of the suspension, change tyre pressures and I'll be able to improve my performance significantly. And the bike is fun!!! It's so light you can throw it around, jump logs and rocks, do a bit of trials work and still have plenty of battery.
I would say it's better than an electric MTB. You have more power and speed for covering easy trails and downhill it's a lot like a mountain bike with the bonus of regen charging of the battery. You still get a workout if the trail is challenging. It's really halfway between a mountain bike and a motocross bike with some of the best bits of both. It's no surprise that the SurRon's are popular as they occupy a niche in so far as price, performance and fun goes that no other manufacturer has matched yet. Definitely great for no wind days, especially if you have a few friends with SurRon's to ride with. And I met a kitesurfer who has one arriving in a couple of weeks. I think he'll be coming down to try it on some local trails

I'd definitely be polite to MTB riders though, otherwise they could get a bit pissed about too many electric bikes ripping on their trails.
If you want to know more about getting one go to
www.surronaustralia.com.au/ as they're the authorised importers especially if you want to go road legal. Adam and Vanessa are the owners and they know their stuff and carry plenty of spares.