I updated my 2010 MBP (8GB RAM, i7, 80GB SSD) to Lion the day it became available and, overall, I'm reasonably happy. However, there are a couple annoyances (bugs or just poor design choices) that I feel are worth mentioning:
1) Mission Control. For heavy users of Spaces and Expose, Mission Control is just a very poor substitute because it loses previously available functionality: (a) you can no longer move windows directly from one desktop to another; there is a "workaround" that requires making the source desktop the active one and then dragging the window to the destination desktop....but even this doesn't work if you want to drag the window to the secondary monitor. (b) you can no longer rotate from the last space to the first one. I know Apple is not targeting people like me (software developers) for its OS, but - common - you can't just take away capabilities without telling people! The Mission Control feature was advertised as combining Spaces & Expose into one elegant, integrated interface - nobody said that it did so at the cost of losing functionality.
2) Choppy scrolling in Safari. Recently - since I started using my MBP's "sleep" mode when moving between home and office rather than shutting down/powering up - Safari "stutters" when scrolling using the touchpad.
3) iPhoto hangs temporarily on startup. Whenever I start iPhoto, there's a 20 second "hang" - the cursor changes to the color wheel and the app is unusable. After the delay, everything works as before. This simply didn't happen before. Very annoying.
4) I have yet to be able to get into my work's VPN again. The Mac OSX built-in VPN for Cisco IPSec never worked for me in Snow Leopard, but there was a free client from Cisco that did. With Lion this client no longer works - and the built-in VPN still doesn't work with our Cisco VPN Concentrator. An Apple engineer contacted me when I posted my troubles in this forum (thanks!). He let me try and log into their VPN (a Cicso ASA) and that worked. We guessed that perhaps we could make our Cisco box work if its firmware was upgraded...an unforeseen expense. If that doesn't work, I'll be forced to buy Cisco's ConnectAnywhere client since that will work on Lion....another unforeseen cost.
I hope this list is useful to people - especially those who have not yet upgraded from Snow Leopard. The discovery of (4) certainly helped my boss who was getting ready to upgrade when I told him.