I'm a novice mountain bike trail rider and i have to say I had an absolute blast sticking only with Hustle and Flow, the novice trail. The trails are very well marked for difficulty levels, and for the novice rider Hustle and Flow has several challenging and fun obstacles including shorter descents that you can cruise or bomb through, some angled terrain, several switchbacks (uphill and downhill) that are nicely banked, roots here and there to provide a bit of a technical challenge without being overwhelming, and some small jumps that you can either take and get some air or you can just ride over (or in many cases, ride beside). At the northern end is a nice little 'drop zone' where you can practice your drop skills off wooden ramps onto a slight downhill. Each drop is marked according to skill level with the novice being a small drop and the expert level having a much larger drop obviously. Portions of a few of the intermediate and expert trails are visible fairly easily from the novice trail and you can catch a look at several of the obstacles to help you decide if you "want to take the plunge" to a higher level of technical difficulty.
The trail is situated in such a way that you can either ride it super hard and really work or you can cruise through some of the features and enjoy yourself. When I was there, I ran into 4 riders, all of whom were quite friendly, although they were all advanced riders so I got out of their way as they were riding and they voiced their appreciation.
The trails are marked quite well for the most part and although the ride isn't enormous, you can do multiple laps on the internal and the external loops for Hustle and Flow. I rode my Trek 820 quite hard through Hustle and Flow and the bike held up fine, as would most non-suspended mountain bikes or inexpensive entry-level bikes. The other riders on the trail (the advanced ones) all had full suspension bikes that definitely cost a few pesos, but i'm not sure if that level of bike is required for the more advanced trails (or if it just makes it more fun).
All in all, the trails were marked well, maintained well, they seemed well thought out, and I had a blast during the first of what will be several visits. Getting to the entrance is easy. Take 56th Avenue East exit off I-5 and follow it all the way east until it hits the dead end, which is about 50 yards from a very visible 'trail entrance' sign for the trails. I spoke to a guy who rides there a few times a month and he says that he hasn't had any problems with break-ins as the trail is becoming more of an attraction, but better safe than sorry (i.e. take your valuables, lock them up, etc).