I like the idea of them. I don't have a huuuge PS2 collection and there's many games I've missed. I also currently don't have a PS2 (I am thinking buying myself one may be a good idea, even if just to keep pristine in a box)
My current options are to play it on my PC with PCSX2, or to play one of these HD collections, which are also gonna be bug free on most games (ICO games have issues with fog in PCSX2), I can get trophies, thats no biggy, but I can also own the things. (I'm not going out n buying games to play on an emulator . Not like I can buy the Team ICO games anyway)
So yeah they're pretty cool for the folks without either a PS2, or the back catalogue that's now slipping from store shelves.
(as for PS1 games I play em on a mix of PS3 but mostly PSP)