If it is well integrated with your browser it's quite ok. Maybe not as convenient as using the same simple password everywhere but certainly a lot better than having to remember a lot of different passwords ;)
I personally prefer _not_ integrating my password manager with my browser, even though the option is available. Instead my password manager performs manually-activated autotyping which, while less convenient, does at least 'feel' like it's more secure.
I trust my OS to isolate applications from eachother more than I trust my browser to isolate extensions from the page they run on. LastPass in particular have had their browser extension exploited[0].
