First amp I ever bought before I knew anything about music gear. Decent starter amp. Onboard effects include basic reverb, delay, flanger, and phaser; these effects are all built into a single knob; thus revealing the limitations of a basic practice amp. That being said, it takes effects pedals pretty well considering its size. Good quality construction though; mine has been through hell and is still running. Definitely needs a new input jack socket, but it still works like new. Great starter amp.
Picked up this amp second hand, it has a few interesting features. 2 channels, one clean one driven, built in FX. I have to be honest, I'm not too into the driven setting (it's a bit like an OD-1) or the effects which are basic at best. I use the clean channel and get all my dirt and modulation from pedals. For home use or jam sessions it's perfectly fine. Would not really hold up too well live or gigging though.
The Marshall MG15DFX is a great amp to begin with, primarily, because of its many effects including: reverb, flange, Delay, and Chorus. It also comes with an overdrive channel, that has a very barky tone, overall a great amp