With OSB being more textured than regular plywood, will I have problems with the glue not covering evenly and ending up with a weak glue job?
Weaker yes, but it shouldn't be a problem as there is still ample surface area. Some additional care would be advisable to ensure a successful bond forms.
Firstly, in case you're unaware wood surfaces to be glued should be freshly worked — that is, they should have been planed, cut, scraped or sanded recently — for a proper glue joint to form. And with sheet goods some sanding is considered a good idea anyway to remove any minor surface contamination it may have accrued during storage and from handling with bare hands.
So lightly sand both surfaces to be glued, spread a thin even layer of glue over both boards (a hard rubber or plastic roller can work well here if you have one) and then bring the boards together and 'clamp' using heavy objects. Use plenty of weight spread around the boards, you can use paint tins (full), stacks of books and even bottles of water to supply the clamping force.
Wood glue is very lubricative, so watch out for some slippage as weight is applied.