I have had one running on my 90L for over two years and it still seems to be going strong. The heater inside packed up a while ago but the filter its self is still going strong like I say and I give it next to no maintnance.
I dont think I would buy other just based on the fact that its internal I would rather go for a cheap external eheim clone or something along those lines, I suppose it depends on price. If its dirt cheap then I probably would but the eheim clones such as atman can be had for about £40 ish now I think. B)