I am not knowledgeable enough about electronics to have my own opinion but from what I've heard from EE's, technicians, and knowledgeable tinkerers, is that when it comes to inverters, you (roughly) get what you pay for. The components needed to make a good solid inverter are not cheap, an inverter can be made cheaply but an inverter that (1) is durable and reliable, and (2) can handle 'inductive loads' and high surge currents (Such as A/C, some power tools, many motors) is not cheap to produce.
So, if your needs are modest, and you just want to power a few gadgets a cheaper inverter might be fine. But if you have power hungry appliances, inductive loads, etc, or want something that (1) should last 15+ years, and (2) can be repaired rather than replaced, a higher quality more robust inverter is the ticket.
Cheaper inverters also often inflate the power ratings, so be aware of that.