I just got mine last week from Costco (32gb one hundred more). I have had Android and iPads in the past (Xoom went back, iPad to my father), so I know my tablets. I love the TouchPad.
WebOS is absolutely the best OS for tablets today. OS only gets you so far, but WebOS is simply the best at multi-tasking, notifications, learning curve, etc. the foundation for the device is spectacular.
The TouchPad also has the most complete browsing experience in tabletland. Whether you want to participate in Jobs' Flash strike is up to you, but the ability to go to Amazon and Wal-Mart/Vudu and simply stream movies is awesome. i can go to Hulu and watch shows without paying for Hulu Plus.
16gb on the device, but 50gb free for life from Box.net.
The limited number of apps can't be denied, though I don't feel a lack of apps. I can read my news, get my weather, email, chat, and play my games. I am sure there are awesome apps I don't have, but I simply don't have time where I don't have them.
The biggest lack on the Touchpad is Office doc editing. While they can be viewed, and there are several nice writing applications. Document editing is still in the "coming soon" list. I don't need it, I use mine for writing, not for spreadsheets or formatted text, but the lack is there and it is significant. I can also open and edit GoogleDocs while on-line and that works ok, but it depends on the strength of the connection.
I have the BT keyboard for longer writing sessions, and it is a great system.
As far as a reputation for lag, I got mine the day of the patch, so I have never noticed any lag.