Hey Willow I have a Mongoose (Crossway 350) too, this is the first time I've seen anyone else admit to having one

Had mine for just over a year, and my commute is 9 miles each way in London so its done a fair few miles. Its been a reliable workhorse, and although quite heavy due to the cromoloy frame and forks, it has been strong enough to survive a crash - knocked over by another cyclist from behind, he was swerving to avoid a black taxi that went too close.
One thing to note when you are paying lowish prices for bikes like £250-£400 is that the manufacturers make cost savings by using crappy saddles and pedals. So in the year I have had my bike I have changed these. Also changed the tyres to Shwalbe Marathons, had these for 6 months and they are puncture free so far.