I'm actually finally playing through the first one now (fresh off the PSN sale the other week). I'm enjoying it; it appeals to the loot hoarder deep within that I thought I had long since abandoned. When I get a shiny new gun that suits my play style, I kind of want to just sit and cuddle it.
Is it weird to say that I wish there was more variety to the guns, though? There are myriad combinations of specs and attachments, but they all seem to be relatively small derivations from around 8 archetypes. They end up looking a lot alike.
The game could also use some effort to stem the tedium and repetition, and some more variety to the environments.
Other than that, there's a lot to like, and I'm excited for the sequel.